Messages

List Conversation Messages

client.conversations.messages.list(, ?, ?): ArrayPage<Message>

get/v1/conversations/{conversation_id}/messages

Send Conversation Message

client.conversations.messages.create(, , ?): LettaResponse { messages, stop_reason, usage } | Stream<LettaStreamingResponse>

post/v1/conversations/{conversation_id}/messages

Retrieve Conversation Stream

client.conversations.messages.stream(, ?, ?): MessageStreamResponse | Stream<LettaStreamingResponse>

post/v1/conversations/{conversation_id}/stream

Compact Conversation

client.conversations.messages.compact(, ?, ?): CompactionResponse { num_messages_after, num_messages_before, summary }

post/v1/conversations/{conversation_id}/compact

ModelsExpand Collapse

CompactionRequest { compaction_settings }

compaction_settings?: CompactionSettings | null

Configuration for conversation compaction / summarization.

model is the only required user-facing field – it specifies the summarizer model handle (e.g. "openai/gpt-4o-mini"). Per-model settings (temperature, max tokens, etc.) are derived from the default configuration for that handle.

model: string

Model handle to use for summarization (format: provider/model-name).

clip_chars?: number | null

The maximum length of the summary in characters. If none, no clipping is performed.

mode?: "all" | "sliding_window"

The type of summarization technique use.

Accepts one of the following:

"all"

"sliding_window"

model_settings?: OpenAIModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 4 more } | AnthropicModelSettings { effort, max_output_tokens, parallel_tool_calls, 6 more } | GoogleAIModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 3 more } | 10 more | null

Optional model settings used to override defaults for the summarizer model.

Accepts one of the following:

OpenAIModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 4 more }

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "openai"

The type of the provider.

reasoning?: Reasoning { reasoning_effort }

The reasoning configuration for the model.

reasoning_effort?: "none" | "minimal" | "low" | 3 more

The reasoning effort to use when generating text reasoning models

Accepts one of the following:

"none"

"minimal"

"low"

"medium"

"high"

"xhigh"

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

strict?: boolean

Enable strict mode for tool calling. When true, tool outputs are guaranteed to match JSON schemas.

temperature?: number

The temperature of the model.

AnthropicModelSettings { effort, max_output_tokens, parallel_tool_calls, 6 more }

effort?: "low" | "medium" | "high" | null

Effort level for Opus 4.5 model (controls token conservation). Not setting this gives similar performance to 'high'.

Accepts one of the following:

"low"

"medium"

"high"

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "anthropic"

The type of the provider.

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

strict?: boolean

Enable strict mode for tool calling. When true, tool outputs are guaranteed to match JSON schemas.

temperature?: number

The temperature of the model.

thinking?: Thinking { budget_tokens, type }

The thinking configuration for the model.

budget_tokens?: number

The maximum number of tokens the model can use for extended thinking.

type?: "enabled" | "disabled"

The type of thinking to use.

Accepts one of the following:

"enabled"

"disabled"

verbosity?: "low" | "medium" | "high" | null

Soft control for how verbose model output should be, used for GPT-5 models.

Accepts one of the following:

"low"

"medium"

"high"

GoogleAIModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 3 more }

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "google_ai"

The type of the provider.

response_schema?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response schema for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

thinking_config?: ThinkingConfig { include_thoughts, thinking_budget }

The thinking configuration for the model.

include_thoughts?: boolean

Whether to include thoughts in the model's response.

thinking_budget?: number

The thinking budget for the model.

GoogleVertexModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 3 more }

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "google_vertex"

The type of the provider.

response_schema?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response schema for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

thinking_config?: ThinkingConfig { include_thoughts, thinking_budget }

The thinking configuration for the model.

include_thoughts?: boolean

Whether to include thoughts in the model's response.

thinking_budget?: number

The thinking budget for the model.

AzureModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 2 more }

Azure OpenAI model configuration (OpenAI-compatible).

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "azure"

The type of the provider.

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

XaiModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 2 more }

xAI model configuration (OpenAI-compatible).

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "xai"

The type of the provider.

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

ZaiModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 3 more }

Z.ai (ZhipuAI) model configuration (OpenAI-compatible).

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "zai"

The type of the provider.

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

thinking?: Thinking { clear_thinking, type }

The thinking configuration for GLM-4.5+ models.

clear_thinking?: boolean

If False, preserved thinking is used (recommended for agents).

type?: "enabled" | "disabled"

Whether thinking is enabled or disabled.

Accepts one of the following:

"enabled"

"disabled"

GroqModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 2 more }

Groq model configuration (OpenAI-compatible).

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "groq"

The type of the provider.

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

DeepseekModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 2 more }

Deepseek model configuration (OpenAI-compatible).

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "deepseek"

The type of the provider.

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

TogetherModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 2 more }

Together AI model configuration (OpenAI-compatible).

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "together"

The type of the provider.

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

BedrockModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 2 more }

AWS Bedrock model configuration.

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "bedrock"

The type of the provider.

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

OpenRouterModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 2 more }

OpenRouter model configuration (OpenAI-compatible).

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "openrouter"

The type of the provider.

response_format?: TextResponseFormat { type } | JsonSchemaResponseFormat { json_schema, type } | JsonObjectResponseFormat { type } | null

The response format for the model.

Accepts one of the following:

TextResponseFormat { type }

Response format for plain text responses.

type?: "text"

The type of the response format.

JsonSchemaResponseFormat { json_schema, type }

Response format for JSON schema-based responses.

json_schema: Record<string, unknown>

The JSON schema of the response.

type?: "json_schema"

The type of the response format.

JsonObjectResponseFormat { type }

Response format for JSON object responses.

type?: "json_object"

The type of the response format.

temperature?: number

The temperature of the model.

ChatGptoAuthModelSettings { max_output_tokens, parallel_tool_calls, provider_type, 2 more }

ChatGPT OAuth model configuration (uses ChatGPT backend API).

max_output_tokens?: number

The maximum number of tokens the model can generate.

parallel_tool_calls?: boolean

Whether to enable parallel tool calling.

provider_type?: "chatgpt_oauth"

The type of the provider.

reasoning?: Reasoning { reasoning_effort }

The reasoning configuration for the model.

reasoning_effort?: "none" | "low" | "medium" | 2 more

The reasoning effort level for GPT-5.x and o-series models.

Accepts one of the following:

"none"

"low"

"medium"

"high"

"xhigh"

temperature?: number

The temperature of the model.

prompt?: string

The prompt to use for summarization.

prompt_acknowledgement?: boolean

Whether to include an acknowledgement post-prompt (helps prevent non-summary outputs).

sliding_window_percentage?: number

The percentage of the context window to keep post-summarization (only used in sliding window mode).

CompactionResponse { num_messages_after, num_messages_before, summary }

num_messages_after: number

num_messages_before: number

summary: string