SDK v1.0 migration guide

Note

This guide covers migrating from Letta SDK v0.x (e.g., 0.1.211) to v1.0 (e.g., 1.0.0+). For agent architecture migrations, see the Architecture Migration Guide.

Caution

Requirements: SDK v1.0 requires either Letta Cloud or self-hosted Letta v0.14+. Earlier self-hosted versions are not compatible with the v1.0 SDK.

Overview

SDK v1.0 introduces breaking changes to improve consistency and align with modern API design patterns:

• Naming convention: All properties now use snake_case instead of camelCase
• Client initialization: Simplified client constructor with renamed parameters
• Method names: Several methods renamed for clarity
• Type imports: Types moved to subpath exports for better organization
• Enums: Replaced with string literal types
• Tool calls: Changed from single object to array structure
• Pagination: List methods now return page objects

Quick Reference

Package Update

Update your package dependency:

package.json

{
  "dependencies": {
-   "@letta-ai/letta-client": "0.1.211"
+   "@letta-ai/letta-client": "1.0.0"
  }
}

pyproject.toml

[tool.poetry.dependencies]
-letta-client = "0.1.324"
+letta-client = "1.0.0"

Import Changes

TypeScript

// Old
- import { LettaClient, Letta } from "@letta-ai/letta-client";

// New
+ import Letta from "@letta-ai/letta-client";
+ import type {
+   Block,
+   CreateBlock,
+   AgentType
+ } from "@letta-ai/letta-client/resources/agents/agents";
+ import type {
+   LettaMessageUnion,
+   ApprovalCreate
+ } from "@letta-ai/letta-client/resources/agents/messages";
+ import type {
+   LlmConfig
+ } from "@letta-ai/letta-client/resources/models/models";

Python

# Old
- from letta_client import Letta, LettaClient

# New
+ from letta_client import Letta
+ from letta_client.schemas.agent import Block, CreateBlock, AgentType
+ from letta_client.schemas.message import LettaMessageUnion, ApprovalCreate
+ from letta_client.schemas.llm_config import LlmConfig

Client Instantiation

TypeScript

// Old
- const client = new LettaClient({
-   token: process.env.LETTA_API_KEY,
-   baseUrl: "https://api.letta.com"
- });

// New
+ const client = new Letta({
+   apiKey: process.env.LETTA_API_KEY,
+   baseURL: "https://api.letta.com"
+ });

Python

# Old
- client = LettaClient(
-     token=os.environ["LETTA_API_KEY"],
-     base_url="https://api.letta.com"
- )

# New
+ client = Letta(
+     api_key=os.environ["LETTA_API_KEY"],
+     base_url="https://api.letta.com"
+ )

Breaking Changes by Category

1. Pagination

All list endpoints now use cursor-based pagination with consistent parameters:

TypeScript

// Old - various pagination styles
const messages = await client.agents.messages.list(agentId, {
  sort_by: "created_at",
  ascending: true
});

// New - standardized cursor pagination
const messagesPage = await client.agents.messages.list(agentId, {
  before: "msg_123",  // cursor (message ID)
  after: "msg_456",   // cursor (message ID)
  limit: 50,
  order: "asc"  // or "desc"
});
const messages = messagesPage.items;

Python

# Old
messages = client.agents.messages.list(
    agent_id=agent_id,
    sort_by="created_at",
    ascending=True
)

# New
messages_page = client.agents.messages.list(
    agent_id=agent_id,
    before="msg_123",
    after="msg_456",
    limit=50,
    order="asc"
)
messages = messages_page.items

Affected endpoints:

• agents.list() - renamed sort_by → order_by, ascending → order
• agents.messages.list()
• agents.tools.list()
• agents.blocks.list()
• agents.files.list()
• agents.folders.list()
• agents.groups.list()
• blocks.list()
• folders.list()
• folders.files.list()
• folders.passages.list()
• folders.agents.list()
• groups.list()
• groups.messages.list()
• identities.list()
• providers.list()
• runs.list()
• runs.messages.list()
• runs.steps.list()
• jobs.list()
• steps.list()
• tags.list()
• tools.list()
• batches.list()
• batches.messages.list()

2. Method Renames and Endpoint Restructuring

Many methods were reorganized for better SDK structure:

TypeScript

// Agent updates
- await client.agents.modify(agentId, updates)
+ await client.agents.update(agentId, updates)

// Message operations
- await client.agents.summarize_agent_conversation(agentId)
+ await client.agents.messages.compact(agentId)

- await client.agents.cancel_agent_run(agentId)
+ await client.agents.messages.cancel(agentId)

- await client.agents.messages.preview_raw_payload(agentId, messages)
+ await client.agents.messages.preview(agentId, messages)

// Agent file operations
- await client.agents.list_agent_files(agentId)
+ await client.agents.files.list(agentId)

// Export/Import
- await client.agents.export_agent_serialized(agentId)
+ await client.agents.exportFile(agentId)

- await client.agents.import_agent_serialized(file)
+ await client.agents.importFile(file)

// Folder operations
- await client.folders.get_agents_for_folder(folderId)
+ await client.folders.agents.list(folderId)

- await client.folders.retrieve_folder_metadata(folderId)
+ await client.folders.retrieve_metadata(folderId)

// Provider operations
- await client.providers.check_provider(providerId)
+ await client.providers.check(providerId)

// Telemetry
- await client.telemetry.retrieve_provider_trace(stepId)
+ await client.steps.trace(stepId)

// Step metrics
- await client.steps.retrieve_step_metrics(stepId)
+ await client.steps.metrics.retrieve(stepId)

// Batch messages
- await client.messages.list_batch_messages(batchId)
+ await client.batches.messages.list(batchId)

// Multi-agent groups
- agent.multi_agent_group
+ agent.managed_group

Python

# Agent updates
- client.agents.modify(agent_id, **updates)
+ client.agents.update(agent_id, **updates)

// Message operations
- client.agents.summarize_agent_conversation(agent_id)
+ client.agents.messages.compact(agent_id)

- client.agents.cancel_agent_run(agent_id)
+ client.agents.messages.cancel(agent_id)

// Export/Import
- client.agents.export_agent_serialized(agent_id)
+ client.agents.export_file(agent_id)

- client.agents.import_agent_serialized(file)
+ client.agents.import_file(file)

// Folder operations
- client.folders.get_agents_for_folder(folder_id)
+ client.folders.agents.list(folder_id)

// Provider operations
- client.providers.check_provider(provider_id)
+ client.providers.check(provider_id)

3. Deprecations

Several endpoints and fields are now deprecated:

Deprecated endpoints:

• client.agents.search() - use client.agents.list() with filters
• client.messages.search() - use client.agents.messages.list() with filters
• client.runs.list_active() - use client.runs.list(active=True)
• client.jobs.list_active() - use client.jobs.list(active=True)
• client.folders.get_by_name() - use client.folders.list(name="...")
• MCP routes under /tools/mcp/servers - replaced with new /mcp-servers endpoints
  • All old MCP methods moved from client.tools.mcp.servers to client.mcp_servers
  • Now use server IDs and tool IDs instead of names
• Sources-related routes - replaced with folders
• Passages routes - replaced with archives
• Legacy agent architecture routes
• All /count endpoints

Deprecated fields:

• agent.memory - use agent.blocks
• step.messages - use client.steps.messages.list(step_id)
• agent.identity_ids - replaced with agent.identities (full objects)
• agent.multi_agent_group - renamed to agent.managed_group
• use_assistant_message parameter - no longer needed
• tool_exec_environment_variables - renamed to secrets

Deprecated on agent/block objects:

• Template-related fields: is_template, base_template_id, deployment_id
• entity_id, preserve_on_migration, hidden
• name on blocks (use label)

4. Property Names (camelCase → snake_case)

All API properties now use snake_case:

TypeScript

// Agent properties
- agent.llmConfig
+ agent.llm_config

- agent.contextWindowLimit
+ agent.context_window_limit

- agent.blockIds
+ agent.block_ids

- agent.includeBaseTools
+ agent.include_base_tools

- agent.includeBaseToolRules
+ agent.include_base_tool_rules

- agent.initialMessageSequence
+ agent.initial_message_sequence

// Message properties
- message.messageType
+ message.message_type

- message.toolCallId
+ message.tool_call_id

- message.toolReturn
+ message.tool_return

- message.toolCall
+ message.tool_calls  // Also changed to array!

// API parameters
- streamTokens: true
+ stream_tokens: true  // Also add streaming: true for streaming requests

- approvalRequestId: id
+ approval_request_id: id

Python

# Agent properties
- agent.llm_config  # Already snake_case
+ agent.llm_config  # No change needed

- agent.context_window_limit
+ agent.context_window_limit  # No change needed

# Python SDK was already using snake_case
# Most changes affect TypeScript/JavaScript only

2. Agent Type Specification

TypeScript

// Old
- agentType: Letta.AgentType.LettaV1Agent

// New
+ agent_type: "letta_v1_agent" as AgentType

Python

# Old
- agent_type=AgentType.LETTA_V1_AGENT

# New
+ agent_type="letta_v1_agent"

3. Method Renames

TypeScript

// Agent updates
- await client.agents.modify(agentId, { model, llmConfig })
+ await client.agents.update(agentId, { model, llm_config })

// Message streaming
- client.agents.messages.createStream(agentId, { messages, streamTokens: true })
+ client.agents.messages.stream(agentId, { messages, stream_tokens: true })

Python

# Agent updates
- client.agents.modify(agent_id, model=model, llm_config=config)
+ client.agents.update(agent_id, model=model, llm_config=config)

# Message streaming
- client.agents.messages.create_stream(agent_id, messages=messages)
+ client.agents.messages.create(agent_id, messages=messages, streaming=True)

4. Message Roles and Stop Reasons

Enums replaced with string literals:

TypeScript

// Message roles
- role: Letta.MessageCreateRole.User
+ role: "user"

// Stop reasons
- if (stopReason === Letta.StopReasonType.EndTurn)
+ if (stopReason === "end_turn")

- if (stopReason === Letta.StopReasonType.RequiresApproval)
+ if (stopReason === "requires_approval")

Python

# Message roles
- role=MessageRole.USER
+ role="user"

# Stop reasons
- if stop_reason == StopReasonType.END_TURN:
+ if stop_reason == "end_turn":

- if stop_reason == StopReasonType.REQUIRES_APPROVAL:
+ if stop_reason == "requires_approval":

5. Tool Calls Structure

Tool calls changed from single object to array:

TypeScript

// Old - single tool_call
- if (message.messageType === "approval_request_message") {
-   const toolCall = message.toolCall;
-   const id = toolCall.toolCallId;
-   const name = toolCall.name;
- }

// New - tool_calls array
+ if (message.message_type === "approval_request_message") {
+   const toolCalls = message.tool_calls || [];
+   if (toolCalls.length > 0) {
+     const toolCall = toolCalls[0];
+     const id = toolCall.tool_call_id;
+     const name = toolCall.name;
+   }
+ }

Python

# Old - single tool_call
- if message.message_type == "approval_request_message":
-     tool_call = message.tool_call
-     id = tool_call.tool_call_id
-     name = tool_call.name

# New - tool_calls array
+ if message.message_type == "approval_request_message":
+     tool_calls = message.tool_calls or []
+     if len(tool_calls) > 0:
+         tool_call = tool_calls[0]
+         id = tool_call.tool_call_id
+         name = tool_call.name

6. Pagination

List methods now return page objects:

TypeScript

// Old
- const messages = await client.agents.messages.list(agentId);

// New
+ const messagesPage = await client.agents.messages.list(agentId);
+ const messages = messagesPage.items;

Python

# Old
- messages = client.agents.messages.list(agent_id=agent_id)

# New
+ messages_page = client.agents.messages.list(agent_id=agent_id)
+ messages = messages_page.items

7. Date Handling

TypeScript

// Old
- date: new Date()

// New
+ date: new Date().toISOString()

Python

# Python handles this automatically
from datetime import datetime
date = datetime.now()  # Works in both versions

8. Archive Management (New APIs)

New endpoints for managing archival memory:

TypeScript

// Create archive
const archive = await client.archives.create({
  name: "my-archive",
  description: "Project knowledge base"
});

// List archives
const archives = await client.archives.list();

// Get archive by ID
const archive = await client.archives.retrieve(archiveId);

// Update archive
await client.archives.update(archiveId, { name: "updated-name" });

// Delete archive
await client.archives.delete(archiveId);

// Attach archive to agent
await client.agents.archives.attach(agentId, archiveId);

// Detach archive from agent
await client.agents.archives.detach(agentId, archiveId);

// List agents using an archive
const agents = await client.archives.agents.list(archiveId);

// Create passages in archive
await client.archives.passages.create(archiveId, { text: "Important fact" });

Python

# Create archive
archive = client.archives.create(
    name="my-archive",
    description="Project knowledge base"
)

# Attach/detach
client.agents.archives.attach(agent_id, archive_id)
client.agents.archives.detach(agent_id, archive_id)

# Create passages
client.archives.passages.create(archive_id, text="Important fact")

9. Identity and Block Management

New attach/detach patterns for identities and blocks:

TypeScript

// Attach identity to agent
await client.agents.identities.attach(agentId, identityId);

// Detach identity from agent
await client.agents.identities.detach(agentId, identityId);

// Attach identity to block
await client.blocks.identities.attach(blockId, identityId);

// Detach identity from block
await client.blocks.identities.detach(blockId, identityId);

// Agent now returns full identity objects
const agent = await client.agents.retrieve(agentId);
// Old: agent.identity_ids = ["id1", "id2"]
// New: agent.identities = [{ id: "id1", name: "Alice", ... }, ...]

Python

# Attach/detach identities
client.agents.identities.attach(agent_id, identity_id)
client.agents.identities.detach(agent_id, identity_id)

# Full identity objects
agent = client.agents.retrieve(agent_id)
for identity in agent.identities:
    print(identity.name)

10. Agent Configuration Updates

New parameters available for agent creation and updates:

TypeScript

// Temperature, top_p, reasoning_effort now available at top level
const agent = await client.agents.create({
  model: "openai/gpt-4",
  temperature: 0.7,
  top_p: 0.9,
  reasoning_effort: "medium",
  max_tokens: 4096,
  context_window_limit: 128000
});

// Update agent configuration
await client.agents.update(agentId, {
  temperature: 0.5,
  context_window_limit: 64000
});

Python

# Create with configuration
agent = client.agents.create(
    model="openai/gpt-4",
    temperature=0.7,
    top_p=0.9,
    reasoning_effort="medium",
    max_tokens=4096,
    context_window_limit=128000
)

# Update configuration
client.agents.update(
    agent_id,
    temperature=0.5
)

11. Message Input Shorthand

Simplified syntax for sending simple user messages:

TypeScript

// Old - verbose
const response = await client.agents.messages.create(agentId, {
  messages: [{
    role: "user",
    content: "Hello!"
  }]
});

// New - shorthand available
const response = await client.agents.messages.create(agentId, {
  input: "Hello!"  // Automatically creates user message
});

// Both forms still supported

Python

# Old
response = client.agents.messages.create(
    agent_id,
    messages=[{"role": "user", "content": "Hello!"}]
)

# New shorthand
response = client.agents.messages.create(
    agent_id,
    input="Hello!"
)

12. Attach/Detach Return Values

All attach/detach endpoints now return None instead of agent/object state:

TypeScript

// Old - returned updated agent
const updatedAgent = await client.agents.tools.attach(agentId, toolId);

// New - returns void/None
await client.agents.tools.attach(agentId, toolId);
// Fetch agent separately if needed
const agent = await client.agents.retrieve(agentId);

Python

# Old
updated_agent = client.agents.tools.attach(agent_id, tool_id)

# New
client.agents.tools.attach(agent_id, tool_id)
agent = client.agents.retrieve(agent_id)

Affected methods:

• agents.tools.attach/detach
• agents.blocks.attach/detach
• agents.folders.attach/detach
• agents.archives.attach/detach
• agents.identities.attach/detach
• blocks.identities.attach/detach

13. Agent Import/Export Changes

Import endpoint now supports name overriding:

TypeScript

// Old - append_copy_suffix parameter
const agent = await client.agents.import(file, {
  append_copy_suffix: true  // Deprecated
});

// New - override_name parameter
const agent = await client.agents.importFile(file, {
  override_name: "my-imported-agent"  // Optional, exact name to use
});

Python

# Old
agent = client.agents.import_agent(
    file,
    append_copy_suffix=True
)

# New
agent = client.agents.import_file(
    file,
    override_name="my-imported-agent"
)

14. Query Parameter to Request Body Changes

Several endpoints moved from query parameters to request body:

TypeScript

// Tool approval settings (was query params, now request body)
await client.agents.tools.update_approval(agentId, toolName, {
  require_approval: true
});

// Reset messages (was query param, now request body)
await client.agents.messages.reset(agentId, {
  add_default_initial_messages: false
});

// Steps feedback (was query params, now request body)
await client.steps.feedback.create(stepId, {
  rating: "positive",
  tags: ["helpful", "accurate"]
});

Python

# Tool approval
client.agents.tools.update_approval(
    agent_id,
    tool_name,
    require_approval=True
)

# Reset messages
client.agents.messages.reset(
    agent_id,
    add_default_initial_messages=False
)

15. Tags Endpoint

Tags list endpoint now uses name parameter instead of query_text:

TypeScript

// Old
const tags = await client.tags.list({ query_text: "important" });

// New
const tags = await client.tags.list({ name: "important" });

Python

# Old
tags = client.tags.list(query_text="important")

# New
tags = client.tags.list(name="important")

16. Project ID Handling

Project ID is now passed in the client constructor or headers:

TypeScript

// Pass in constructor
const client = new Letta({
  apiKey: process.env.LETTA_API_KEY,
  projectId: "proj_123"
});

// No longer in URL paths
- await client.templates.agents.create("proj_123", templateVersion, data)
+ await client.templates.agents.create(templateVersion, data)

Python

# Pass in constructor
client = Letta(
    api_key=os.environ["LETTA_API_KEY"],
    project_id="proj_123"
)

17. MCP (Model Context Protocol) Server Management

MCP routes have been completely restructured with new endpoints under /mcp-servers:

TypeScript

// OLD ROUTES (under /tools/mcp/servers - DEPRECATED)
// Using server names and tool names

// List MCP servers
- const servers = await client.tools.mcp.servers.list();

// Add MCP server
- await client.tools.mcp.servers.create(serverConfig);

// Update MCP server by name
- await client.tools.mcp.servers.update(serverName, updateConfig);

// Delete MCP server by name
- await client.tools.mcp.servers.delete(serverName);

// List tools from a server by name
- const tools = await client.tools.mcp.servers.tools.list(serverName);

// Add individual tool by name
- await client.tools.mcp.servers.tools.add(serverName, toolName);

// Resync tools
- await client.tools.mcp.servers.resync(serverName);

// Execute tool by names
- await client.tools.mcp.servers.tools.execute(serverName, toolName, { args });

// Connect to server (for OAuth)
- await client.tools.mcp.servers.connect(serverConfig);

// NEW ROUTES (under /mcp-servers)
// Using server IDs and tool IDs

// List MCP servers (returns array of server objects with IDs)
+ const servers = await client.mcp_servers.list();

// Create MCP server (automatically syncs tools)
+ const server = await client.mcp_servers.create(serverConfig);
+ // Returns: { id: "mcp_server_123", name: "...", ... }

// Get MCP server by ID
+ const server = await client.mcp_servers.retrieve(serverId);

// Update MCP server by ID
+ await client.mcp_servers.update(serverId, updateConfig);

// Delete MCP server by ID
+ await client.mcp_servers.delete(serverId);

// List tools from a server by ID
+ const tools = await client.mcp_servers.tools.list(serverId);

// Get specific tool by ID
+ const tool = await client.mcp_servers.tools.retrieve(serverId, toolId);

// Run/execute tool by ID
+ const result = await client.mcp_servers.tools.run(serverId, toolId, {
+   args: { key: "value" }
+ });

// Refresh tools (replaces resync)
+ await client.mcp_servers.refresh(serverId);

// Connect to server (for OAuth) - now uses server ID
+ await client.mcp_servers.connect(serverId);

Python

# OLD ROUTES (DEPRECATED)
- servers = client.tools.mcp.servers.list()
- client.tools.mcp.servers.create(server_config)
- client.tools.mcp.servers.update(server_name, update_config)
- client.tools.mcp.servers.delete(server_name)
- tools = client.tools.mcp.servers.tools.list(server_name)
- client.tools.mcp.servers.tools.add(server_name, tool_name)
- client.tools.mcp.servers.resync(server_name)
- client.tools.mcp.servers.tools.execute(server_name, tool_name, args=args)

# NEW ROUTES
+ servers = client.mcp_servers.list()
+ server = client.mcp_servers.create(server_config)
+ server = client.mcp_servers.retrieve(server_id)
+ client.mcp_servers.update(server_id, update_config)
+ client.mcp_servers.delete(server_id)
+ tools = client.mcp_servers.tools.list(server_id)
+ tool = client.mcp_servers.tools.retrieve(server_id, tool_id)
+ result = client.mcp_servers.tools.run(server_id, tool_id, args={"key": "value"})
+ client.mcp_servers.refresh(server_id)
+ client.mcp_servers.connect(server_id)

Key Changes:

• Namespace: Moved from client.tools.mcp.servers to client.mcp_servers
• Identification: Use server IDs and tool IDs instead of names
  • Old: serverName (string) → New: serverId (ID string like "mcp_server_123")
  • Old: toolName (string) → New: toolId (ID string like "tool_456")
• Tool Management: Tools are now automatically synced when creating a server
  • No longer need to manually “add” individual tools
  • Use refresh() to resync tools (replaces resync())
• Tool Execution: Method renamed from execute() to run()
• Server Retrieval: New retrieve() method to get individual server by ID
• Tool Retrieval: New retrieve() method to get individual tool by ID

Migration Example:

TypeScript

// Before: Using names
const servers = await client.tools.mcp.servers.list();
const myServer = servers.find(s => s.name === "my-server");
const tools = await client.tools.mcp.servers.tools.list("my-server");
const myTool = tools.find(t => t.name === "my-tool");
await client.tools.mcp.servers.tools.execute("my-server", "my-tool", {
  args: { query: "hello" }
});

// After: Using IDs
const servers = await client.mcp_servers.list();
const myServer = servers.find(s => s.name === "my-server");
const serverId = myServer.id;  // Get ID from server object
const tools = await client.mcp_servers.tools.list(serverId);
const myTool = tools.find(t => t.name === "my-tool");
const toolId = myTool.id;  // Get ID from tool object
await client.mcp_servers.tools.run(serverId, toolId, {
  args: { query: "hello" }
});

Python

# Before
servers = client.tools.mcp.servers.list()
my_server = next(s for s in servers if s.name == "my-server")
tools = client.tools.mcp.servers.tools.list("my-server")
my_tool = next(t for t in tools if t.name == "my-tool")
client.tools.mcp.servers.tools.execute(
    "my-server",
    "my-tool",
    args={"query": "hello"}
)

# After
servers = client.mcp_servers.list()
my_server = next(s for s in servers if s.name == "my-server")
server_id = my_server.id
tools = client.mcp_servers.tools.list(server_id)
my_tool = next(t for t in tools if t.name == "my-tool")
tool_id = my_tool.id
client.mcp_servers.tools.run(
    server_id,
    tool_id,
    args={"query": "hello"}
)

Notes:

• MCP servers and tools now have persistent IDs in the database
• Server names are no longer unique identifiers - use IDs instead
• Tool schemas are automatically kept in sync via the refresh() endpoint
• The old routes under /tools/mcp/servers are deprecated and will be removed

Migration Examples

Complete Agent Creation

TypeScript

// Before
const agent = await client.agents.create({
  agentType: Letta.AgentType.LettaV1Agent,
  model: "openai/gpt-4",
  contextWindowLimit: 200_000,
  blockIds: ["block-1", "block-2"],
  includeBaseTools: false,
  includeBaseToolRules: false,
  initialMessageSequence: [],
});

// After
const agent = await client.agents.create({
  agent_type: "letta_v1_agent" as AgentType,
  model: "openai/gpt-4",
  context_window_limit: 200_000,
  block_ids: ["block-1", "block-2"],
  include_base_tools: false,
  include_base_tool_rules: false,
  initial_message_sequence: [],
});

Python

# Before
agent = client.agents.create(
    agent_type=AgentType.LETTA_V1_AGENT,
    model="openai/gpt-4",
    context_window_limit=200_000,
    block_ids=["block-1", "block-2"],
    include_base_tools=False,
    include_base_tool_rules=False,
    initial_message_sequence=[],
)

# After
agent = client.agents.create(
    agent_type="letta_v1_agent",
    model="openai/gpt-4",
    context_window_limit=200_000,
    block_ids=["block-1", "block-2"],
    include_base_tools=False,
    include_base_tool_rules=False,
    initial_message_sequence=[],
)

Streaming Messages

TypeScript

// Before
const stream = await client.agents.messages.createStream(agentId, {
  messages: [{
    role: Letta.MessageCreateRole.User,
    content: "Hello"
  }],
  streamTokens: true,
});

// After
const stream = await client.agents.messages.stream(agentId, {
  messages: [{
    role: "user",
    content: "Hello"
  }],
  stream_tokens: true,
});

Python

# Before
stream = client.agents.messages.create_stream(
    agent_id=agent_id,
    messages=[{"role": "user", "content": "Hello"}],
    stream_tokens=True,
)

# After
stream = client.agents.messages.create(
    agent_id=agent_id,
    messages=[{"role": "user", "content": "Hello"}],
    streaming=True,
    stream_tokens=True,
)

Handling Approvals

TypeScript

// Before
if (message.messageType === "approval_request_message") {
  const toolCall = message.toolCall;
  await client.agents.messages.create(agentId, {
    messages: [{
      type: "approval",
      approvalRequestId: toolCall.toolCallId,
      approve: true,
    }],
  });
}

// After
if (message.message_type === "approval_request_message") {
  const toolCalls = message.tool_calls || [];
  if (toolCalls.length > 0) {
    const toolCall = toolCalls[0];
    await client.agents.messages.create(agentId, {
      messages: [{
        type: "approval",
        approval_request_id: toolCall.tool_call_id,
        approve: true,
      }],
    });
  }
}

Python

# Before
if message.message_type == "approval_request_message":
    tool_call = message.tool_call
    client.agents.messages.create(
        agent_id=agent_id,
        messages=[{
            "type": "approval",
            "approval_request_id": tool_call.tool_call_id,
            "approve": True,
        }],
    )

# After
if message.message_type == "approval_request_message":
    tool_calls = message.tool_calls or []
    if len(tool_calls) > 0:
        tool_call = tool_calls[0]
        client.agents.messages.create(
            agent_id=agent_id,
            messages=[{
                "type": "approval",
                "approval_request_id": tool_call.tool_call_id,
                "approve": True,
            }],
        )

Updating Agent Configuration

TypeScript

// Before
await client.agents.modify(agentId, {
  model: "openai/gpt-4",
  llmConfig: { temperature: 0.7 }
});
const agent = await client.agents.retrieve(agentId);
const config = agent.llmConfig;

// After
await client.agents.update(agentId, {
  model: "openai/gpt-4",
  llm_config: { temperature: 0.7 }
});
const agent = await client.agents.retrieve(agentId);
const config = agent.llm_config;

Python

# Before
client.agents.modify(
    agent_id=agent_id,
    model="openai/gpt-4",
    llm_config={"temperature": 0.7}
)
agent = client.agents.retrieve(agent_id=agent_id)
config = agent.llm_config

# After
client.agents.update(
    agent_id=agent_id,
    model="openai/gpt-4",
    llm_config={"temperature": 0.7}
)
agent = client.agents.retrieve(agent_id=agent_id)
config = agent.llm_config

Migration Checklist

Use this checklist to ensure a complete migration:

Core SDK Changes:

• Update package version to 1.0.0-alpha.10 or later
• Update all imports (client and types)
• Replace LettaClient with Letta
• Update client constructor params: token → apiKey, baseUrl → baseURL
• Add projectId to client constructor if using multi-project setup
• Convert all property names from camelCase to snake_case
• Replace enum references with string literals
• Convert Date objects to ISO strings where required
• Update type annotations to use new import paths

Method Renames:

• Update modify() calls to update()
• Update createStream() calls to create() with streaming: true
• Rename summarize_agent_conversation() → messages.compact()
• Rename cancel_agent_run() → messages.cancel()
• Rename preview_raw_payload() → messages.preview()
• Rename list_agent_files() → files.list()
• Rename export_agent_serialized() → export_file()
• Rename import_agent_serialized() → import_file()
• Rename folder/provider method names (see section 2)
• Update telemetry routes to use steps.trace()

Pagination:

• Update all list methods to access .items property
• Replace sort_by with order_by in agents.list()
• Replace ascending with order parameter
• Update pagination parameters: before, after, limit, order
• Handle cursor-based pagination for all list endpoints

Message Handling:

• Handle tool_calls as an array instead of single object
• Update identity_ids references to use identities (full objects)
• Replace agent.memory with agent.blocks
• Update step.messages to use steps.messages.list()
• Consider using new input shorthand for simple messages

Deprecations:

• Remove usage of deprecated search endpoints
• Replace list_active() with list(active=True)
• Remove use_assistant_message parameter
• Replace tool_exec_environment_variables with secrets
• Remove template-related fields from agent/block objects
• Replace sources endpoints with folders
• Replace passages endpoints with archives

New Features:

• Update attach/detach methods (now return None)
• Use new archive management APIs if needed
• Update agent import to use override_name instead of append_copy_suffix
• Move query parameters to request body for affected endpoints
• Use new agent configuration parameters (temperature, top_p, etc.)

MCP (Model Context Protocol) Changes:

• Migrate from client.tools.mcp.servers to client.mcp_servers
• Update MCP server references to use IDs instead of names
• Update MCP tool references to use IDs instead of names
• Remove manual tool “add” operations (tools auto-sync on server create)
• Replace resync() calls with refresh()
• Replace execute() calls with run()
• Add server/tool ID lookup logic if using names
• Update OAuth connection flow to use server IDs

Testing:

• Test all agent operations (create, update, message)
• Test streaming and approval flows
• Verify memory block operations still work
• Test pagination on list endpoints
• Test archive management if used
• Verify identity/block attach/detach operations
• Test agent import/export

Automated Migration Tools

Find and Replace Script

Use this script to help automate common replacements:

Shell (TypeScript projects)

# Install dependencies
npm install -g jscodeshift

# Run find-and-replace (adjust paths as needed)
find src -name "*.ts" -o -name "*.tsx" | xargs sed -i '' \
  -e 's/LettaClient/Letta/g' \
  -e 's/\.modify(/.update(/g' \
  -e 's/\.createStream(/.create(/g' \
  -e 's/\.messageType/.message_type/g' \
  -e 's/\.toolCall/.tool_calls/g' \
  -e 's/\.toolCallId/.tool_call_id/g' \
  -e 's/\.toolReturn/.tool_return/g' \
  -e 's/llmConfig/llm_config/g' \
  -e 's/streamTokens/stream_tokens/g' \
  -e 's/\.tools\.mcp\.servers/\.mcp_servers/g' \
  -e 's/\.resync(/\.refresh(/g'

# Note: MCP server/tool name -> ID migration requires manual intervention
# as you need to fetch IDs from the API

Python (migration helper)

import re
from pathlib import Path

def migrate_file(filepath: Path):
    """Apply SDK v1.0 migration patterns to a Python file"""
    content = filepath.read_text()

    # Import updates
    content = re.sub(
        r'from letta_client import LettaClient',
        r'from letta_client import Letta',
        content
    )

    # Method renames
    content = content.replace('.modify(', '.update(')
    content = content.replace('.create_stream(', '.stream(')

    # MCP namespace changes
    content = content.replace('.tools.mcp.servers', '.mcp_servers')
    content = content.replace('.resync(', '.refresh(')

    # Already using snake_case in Python, but fix any camelCase
    content = re.sub(r'messageType', 'message_type', content)
    content = re.sub(r'toolCall([^_])', r'tool_calls\1', content)

    filepath.write_text(content)
    print(f"✓ Migrated {filepath}")

# Usage
for py_file in Path('src').rglob('*.py'):
    migrate_file(py_file)

Caution

Always review automated changes! These scripts help with common patterns but cannot handle all edge cases. Test thoroughly after migration.

Troubleshooting

”Property ‘llmConfig’ does not exist” (TypeScript)

Cause: Property renamed to llm_config

Fix: Update all references to use snake_case

- agent.llmConfig
+ agent.llm_config

”Cannot read property ‘toolCallId’ of undefined”

Cause: tool_call changed to tool_calls (array)

Fix: Access the first element of the array

- const id = message.toolCall.toolCallId;
+ const toolCalls = message.tool_calls || [];
+ const id = toolCalls[0]?.tool_call_id;

”items is not iterable”

Cause: Trying to iterate over page object instead of items array

Fix: Access the .items property first

- for (const message of messages) {
+ const messagesPage = await client.agents.messages.list(agentId);
+ for (const message of messagesPage.items) {

”Cannot find module ‘@letta-ai/letta-client/resources/…’”

Cause: Types moved to subpath exports

Fix: Update imports to use new subpaths

- import { Letta } from "@letta-ai/letta-client";
+ import type { Block } from "@letta-ai/letta-client/resources/agents/agents";

”Method ‘modify’ does not exist”

Cause: Method renamed to update

Fix: Update all modify calls

- await client.agents.modify(agentId, updates)
+ await client.agents.update(agentId, updates)

”Cannot access property ‘identity_ids’”

Cause: Field renamed to identities and now returns full objects

Fix: Access the identities array and extract IDs if needed

- const ids = agent.identity_ids;
+ const identities = agent.identities;
+ const ids = identities.map(i => i.id);

”Pagination parameters ‘sort_by’ or ‘ascending’ not recognized”

Cause: Pagination parameters standardized to order_by and order

Fix: Update parameter names

- await client.agents.list({ sort_by: "created_at", ascending: true })
+ await client.agents.list({ order_by: "created_at", order: "asc" })

”Attach/detach methods return undefined”

Cause: These methods now return None/void instead of updated state

Fix: Fetch the object separately if you need the updated state

await client.agents.tools.attach(agentId, toolId);
const agent = await client.agents.retrieve(agentId);  // Get updated state

”Cannot find method ‘summarize_agent_conversation’”

Cause: Method moved to messages subresource

Fix: Use the new path

- await client.agents.summarize_agent_conversation(agentId)
+ await client.agents.messages.compact(agentId)

”Query parameter ‘add_default_initial_messages’ not working”

Cause: Parameter moved from query to request body

Fix: Pass as request body parameter

- await client.agents.messages.reset(agentId, { params: { add_default_initial_messages: false } })
+ await client.agents.messages.reset(agentId, { add_default_initial_messages: false })

”Cannot find ‘client.tools.mcp.servers’”

Cause: MCP routes moved to new namespace

Fix: Use new MCP server methods

- await client.tools.mcp.servers.list()
+ await client.mcp_servers.list()

”MCP server not found by name”

Cause: MCP methods now use server IDs instead of names

Fix: Lookup server ID from name first

// Get server ID from name
const servers = await client.mcp_servers.list();
const myServer = servers.find(s => s.name === "my-server");
const serverId = myServer.id;

// Use ID for subsequent operations
await client.mcp_servers.tools.list(serverId);

”MCP tool ‘toolName’ not found”

Cause: MCP tool execution now uses tool IDs instead of names

Fix: Lookup tool ID from name first

const tools = await client.mcp_servers.tools.list(serverId);
const myTool = tools.find(t => t.name === "my-tool");
const toolId = myTool.id;

await client.mcp_servers.tools.run(serverId, toolId, { args });

”Method ‘execute’ not found on mcp_servers.tools”

Cause: Method renamed from execute() to run()

Fix: Use the new method name

- await client.mcp_servers.tools.execute(serverId, toolId, { args })
+ await client.mcp_servers.tools.run(serverId, toolId, { args })

Additional Resources

• Architecture Migration Guide - For migrating agent architectures
• API Reference - Complete SDK documentation
• Changelog - All SDK changes
• GitHub - Source code and issues
• Discord - Get help from the community

Getting Help

If you encounter issues during migration:

1. Check the Changelog for detailed release notes
2. Search GitHub Issues for known problems
3. Ask in Discord #dev-help for community support
4. Contact [email protected] for enterprise support