Letta Multi-Agent Groups API

openapi: 3.0.3
info:
  title: Letta Agent Templates Multi-Agent Groups API
  description: The Letta API creates and operates stateful AI agents whose memory - core context blocks and archival vector memory - persists across sessions. It configures the tools, data sources, identities, and multi-agent groups an agent uses, sends and streams messages to agents, and inspects the runs, jobs, and steps behind every agent response. The same OpenAPI-documented interface is served by the managed Letta Cloud API and by the open-source, self-hostable Letta server. All requests require a Bearer API key.
  version: 1.0.0
  contact:
    name: Letta
    url: https://www.letta.com
  license:
    name: Apache-2.0
    url: https://github.com/letta-ai/letta/blob/main/LICENSE
servers:
- url: https://api.letta.com/v1
  description: Letta Cloud
- url: http://localhost:8283/v1
  description: Self-hosted (default local port)
security:
- bearerAuth: []
tags:
- name: Multi-Agent Groups
  description: Groups of agents coordinating around shared memory.
paths:
  /v1/groups/:
    get:
      tags:
      - Multi-Agent Groups
      summary: List Groups
      description: Fetch all multi-agent groups matching query.
      parameters:
      - name: manager_type
        in: query
        required: false
        description: Search groups by manager type
        schema:
          type: string
      - name: before
        in: query
        required: false
        description: Group ID cursor for pagination. Returns groups that come before this group ID in the specified sort order
        schema:
          type: string
      - name: after
        in: query
        required: false
        description: Group ID cursor for pagination. Returns groups that come after this group ID in the specified sort order
        schema:
          type: string
      - name: limit
        in: query
        required: false
        description: Maximum number of groups to return
        schema:
          type: string
          default: 50
      - name: order
        in: query
        required: false
        description: Sort order for groups by creation time. 'asc' for oldest first, 'desc' for newest first
        schema:
          type: string
          default: asc
          enum:
          - asc
          - desc
      - name: order_by
        in: query
        required: false
        description: Field to sort by
        schema:
          type: string
          default: created_at
      - name: project_id
        in: query
        required: false
        description: Search groups by project id
        schema:
          type: string
      deprecated: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: array
                    items:
                      $ref: '#/components/schemas/Group'
        '401':
          $ref: '#/components/responses/Unauthorized'
    post:
      tags:
      - Multi-Agent Groups
      summary: Create Group
      description: Create a new multi-agent group with the specified configuration.
      deprecated: true
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateGroupRequest'
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Group'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/groups/count:
    get:
      tags:
      - Multi-Agent Groups
      summary: Count Groups
      description: Get the count of all groups associated with a given user.
      deprecated: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
  /v1/groups/{group_id}:
    get:
      tags:
      - Multi-Agent Groups
      summary: Retrieve Group
      description: Retrieve the group by id.
      parameters:
      - name: group_id
        in: path
        required: true
        description: The ID of the group in the format 'group-<uuid4>'
        schema:
          type: string
      deprecated: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Group'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
    patch:
      tags:
      - Multi-Agent Groups
      summary: Modify Group
      description: Create a new multi-agent group with the specified configuration.
      parameters:
      - name: group_id
        in: path
        required: true
        description: The ID of the group in the format 'group-<uuid4>'
        schema:
          type: string
      deprecated: true
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateGroupRequest'
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Group'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/ValidationError'
    delete:
      tags:
      - Multi-Agent Groups
      summary: Delete Group
      description: Delete a multi-agent group.
      parameters:
      - name: group_id
        in: path
        required: true
        description: The ID of the group in the format 'group-<uuid4>'
        schema:
          type: string
      deprecated: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
  /v1/groups/{group_id}/blocks/attach/{block_id}:
    patch:
      tags:
      - Multi-Agent Groups
      summary: Attach Block To Group
      description: 'Attach a block to a group.

        This will add the block to the group and all agents within the group.'
      parameters:
      - name: block_id
        in: path
        required: true
        schema:
          type: string
      - name: group_id
        in: path
        required: true
        description: The ID of the group in the format 'group-<uuid4>'
        schema:
          type: string
      deprecated: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/groups/{group_id}/blocks/detach/{block_id}:
    patch:
      tags:
      - Multi-Agent Groups
      summary: Detach Block From Group
      description: 'Detach a block from a group.

        This will remove the block from the group and all agents within the group.'
      parameters:
      - name: block_id
        in: path
        required: true
        schema:
          type: string
      - name: group_id
        in: path
        required: true
        description: The ID of the group in the format 'group-<uuid4>'
        schema:
          type: string
      deprecated: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/ValidationError'
  /v1/groups/{group_id}/messages:
    get:
      tags:
      - Multi-Agent Groups
      summary: List Group Messages
      description: Retrieve message history for an agent.
      parameters:
      - name: group_id
        in: path
        required: true
        description: The ID of the group in the format 'group-<uuid4>'
        schema:
          type: string
      - name: before
        in: query
        required: false
        description: Message ID cursor for pagination. Returns messages that come before this message ID in the specified sort order
        schema:
          type: string
      - name: after
        in: query
        required: false
        description: Message ID cursor for pagination. Returns messages that come after this message ID in the specified sort order
        schema:
          type: string
      - name: limit
        in: query
        required: false
        description: Maximum number of messages to retrieve
        schema:
          type: string
          default: 10
      - name: order
        in: query
        required: false
        description: Sort order for messages by creation time. 'asc' for oldest first, 'desc' for newest first
        schema:
          type: string
          default: desc
          enum:
          - asc
          - desc
      - name: order_by
        in: query
        required: false
        description: Field to sort by
        schema:
          type: string
          default: created_at
      - name: use_assistant_message
        in: query
        required: false
        description: Whether to use assistant messages
        schema:
          type: boolean
          default: true
      - name: assistant_message_tool_name
        in: query
        required: false
        description: The name of the designated message tool.
        schema:
          type: string
          default: send_message
      - name: assistant_message_tool_kwarg
        in: query
        required: false
        description: The name of the message argument.
        schema:
          type: string
          default: message
      - name: include_return_message_types
        in: query
        required: false
        description: Message types to include in response. When null, all message types are returned.
        schema:
          type: string
      deprecated: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                properties:
                  data:
                    type: array
                    items:
                      $ref: '#/components/schemas/LettaMessage'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
  /v1/groups/{group_id}/reset-messages:
    patch:
      tags:
      - Multi-Agent Groups
      summary: Reset Group Messages
      description: Delete the group messages for all agents that are part of the multi-agent group.
      parameters:
      - name: group_id
        in: path
        required: true
        description: The ID of the group in the format 'group-<uuid4>'
        schema:
          type: string
      deprecated: true
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '422':
          $ref: '#/components/responses/ValidationError'
components:
  schemas:
    LettaMessage:
      type: object
      description: A single message in an agent conversation (user, assistant, tool call/return, or reasoning).
      properties:
        id:
          type: string
        message_type:
          type: string
          enum:
          - user_message
          - assistant_message
          - reasoning_message
          - tool_call_message
          - tool_return_message
          - system_message
        content:
          type: string
        date:
          type: string
          format: date-time
    Group:
      type: object
      description: A multi-agent group coordinating several agents around shared memory.
      properties:
        id:
          type: string
        description:
          type: string
        manager_type:
          type: string
          enum:
          - round_robin
          - supervisor
          - dynamic
          - sleeptime
          - voice_sleeptime
        manager_agent_id:
          type: string
        agent_ids:
          type: array
          items:
            type: string
        shared_block_ids:
          type: array
          items:
            type: string
        termination_token:
          type: string
        max_turns:
          type: integer
    HTTPValidationError:
      type: object
      properties:
        detail:
          type: array
          items:
            type: object
            properties:
              loc:
                type: array
                items:
                  type: string
              msg:
                type: string
              type:
                type: string
    Error:
      type: object
      properties:
        error:
          type: object
          properties:
            message:
              type: string
            code:
              type: string
    CreateGroupRequest:
      type: object
      required:
      - agent_ids
      - manager_config
      properties:
        description:
          type: string
        agent_ids:
          type: array
          items:
            type: string
        shared_block_ids:
          type: array
          items:
            type: string
        manager_config:
          type: object
          additionalProperties: true
  responses:
    Unauthorized:
      description: Missing or invalid Bearer API key.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: The requested resource was not found.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    ValidationError:
      description: The request payload failed validation.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/HTTPValidationError'
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: 'API key created at https://app.letta.com/api-keys, passed as `Authorization: Bearer YOUR_API_KEY`.'