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Letta

Letta Tools API

Register and execute custom tools (sandboxed Python, client-side, MCP).

Documentation Provider Profile APIs.io OpenAPI GitHub

Letta Tools API is one of 41 APIs that Letta publishes on the APIs.io network, described by a machine-readable OpenAPI specification.

This API exposes 14 JSON Schema definitions.

Tagged areas include Tools. The published artifact set on APIs.io includes an OpenAPI specification, API documentation, pricing, a changelog, and 14 JSON Schemas.

This API exposes 21 operations across 15 paths, and defines 30 schemas. It is described by OpenAPI 3.1.0, at version 1.0.0.

Requests are made against 3 base URLs: https://api.letta.com, https://app.letta.com, http://localhost:8283.

21 operations 15 paths 30 schemas 2 DELETE6 GET2 PATCH9 POST2 PUT

Metadata

The identity and technical contract details declared by the specification.

Specification
OpenAPI 3.1.0
API Version
1.0.0
Base URL
https://api.letta.com
Authentication
HTTP Bearer
Contact
Letta
License
Apache-2.0
Resource Areas
1

Authentication & Security 1

Letta Tools API declares 1 security scheme for authenticating requests. It accepts HTTP bearer tokens (bearerAuth). By default, every request must be authenticated.

Paths & Operations 21

Across 15 paths, the API surfaces 21 operations — 2 DELETE, 6 GET, 2 PATCH, 9 POST, 2 PUT. Each is listed below with its method, path, parameters, and response codes.

Tools 21

Register and execute custom tools (sandboxed Python, client-side, MCP).

DELETE
/v1/tools/{tool_id}
Delete Tool
delete_tool 1 param → 200422
GET
/v1/tools/{tool_id}
Retrieve Tool
retrieve_tool 1 param → 200422
PATCH
/v1/tools/{tool_id}
Modify Tool
modify_tool 1 param body → 200422
GET
/v1/tools/count
Count Tools
count_tools 8 params → 200422
GET
/v1/tools/
List Tools
list_tools 12 params → 200422
POST
/v1/tools/
Create Tool
create_tool body → 200422
PUT
/v1/tools/
Upsert Tool
upsert_tool body → 200422
POST
/v1/tools/search
Search Tools
search_tools body → 200422
POST
/v1/tools/add-base-tools
Upsert Base Tools
add_base_tools → 200422
POST
/v1/tools/run
Run Tool from Source
run_tool_from_source body → 200422
GET
/v1/tools/mcp/servers
List MCP Servers
list_mcp_servers → 200422
PUT
/v1/tools/mcp/servers
Add MCP Server to Config
add_mcp_server body → 200422
GET
/v1/tools/mcp/servers/{mcp_server_name}/tools
List MCP Tools by Server
list_mcp_tools_by_server 1 param → 200422
POST
/v1/tools/mcp/servers/{mcp_server_name}/resync
Resync MCP Server Tools
resync_mcp_server_tools 2 params → 200422
POST
/v1/tools/mcp/servers/{mcp_server_name}/{mcp_tool_name}
Add MCP Tool
add_mcp_tool 2 params → 200422
PATCH
/v1/tools/mcp/servers/{mcp_server_name}
Update MCP Server
update_mcp_server 1 param body → 200422
DELETE
/v1/tools/mcp/servers/{mcp_server_name}
Delete MCP Server from Config
delete_mcp_server 1 param → 200422
POST
/v1/tools/mcp/servers/test
Test MCP Server
test_mcp_server body → 200422
POST
/v1/tools/mcp/servers/connect
Connect MCP Server
connect_mcp_server body → 200422
POST
/v1/tools/mcp/servers/{mcp_server_name}/tools/{tool_name}/execute
Execute MCP Tool
execute_mcp_tool 2 params body → 200422
GET
/v1/tools/mcp/oauth/callback
MCP Oauth Callback
mcp_oauth_callback 4 params → 200422

Schemas 30

The contract defines 30 schemas that model the data the API accepts and returns. The most detailed are Tool (18 properties), ToolReturnMessage (16 properties), ToolUpdate (12 properties), ToolCreate (11 properties). Each schema is shown below with its type and property counts.

Tool
object
Representation of a tool, which is a function that can be called by the agent.
18 properties
ImageContent
object
2 properties 1 required
ToolType
string
letta__schemas__mcp__UpdateStreamableHTTPMCPServer
object
Update a Streamable HTTP MCP server
5 properties
MCPToolHealth
object
Health status for an MCP tool's schema.
2 properties 1 required
ToolSearchResult
object
Result from a tool search operation.
5 properties 2 required
NpmRequirement
object
2 properties 1 required
HTTPValidationError
object
1 property
letta__schemas__letta_message__ToolReturn
object
6 properties 3 required
TextContent
object
3 properties 1 required
ToolReturnMessage
object
A message representing the return value of a tool call (generated by Letta executing the requested tool). Args: id (str): The ID of the message date (datetime)…
16 properties 5 required
LettaToolReturnContentUnion
letta__server__rest_api__routers__v1__tools__ToolExecuteRequest
object
1 property
ToolUpdate
object
12 properties
ToolRunFromSource
object
9 properties 2 required
MCPTool
object
A simple wrapper around MCP's tool definition (to avoid conflict with our own)
8 properties 2 required
Base64Image
object
4 properties 2 required
ToolSearchRequest
object
Request model for searching tools using semantic search.
5 properties
letta__schemas__mcp__UpdateStdioMCPServer
object
Update a Stdio MCP server
2 properties
ValidationError
object
3 properties 3 required
StreamableHTTPServerConfig
object
Configuration for an MCP server using Streamable HTTP
6 properties 2 required
MCPServerType
string
LettaImage
object
5 properties 1 required
UrlImage
object
2 properties 1 required
letta__schemas__mcp__UpdateSSEMCPServer
object
Update an SSE MCP server
4 properties
SSEServerConfig
object
Configuration for an MCP server using SSE
6 properties 2 required
PipRequirement
object
2 properties 1 required
ToolAnnotations
object
Additional properties describing a Tool to clients. NOTE: all properties in ToolAnnotations are hints. They are not guaranteed to provide a faithful descriptio…
5 properties
ToolCreate
object
11 properties 1 required
StdioServerConfig
object
5 properties 3 required

Specification

The full machine-readable OpenAPI contract behind this narrative.

Source

letta-tools-api-openapi.yml Raw ↑

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Letta Conversations API
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Letta Device Storage API
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Letta Embeddings API
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Letta Environments API
AE Profile APIs.io
Letta Feeds API
AE Profile APIs.io
#Tools
← Back to L APIs
API Details
ID
letta:letta-tools-api
Base URL
https://api.letta.com
Docs
https://docs.letta.com/
Provider
Letta
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