Letta Blocks API

openapi: 3.2.0
info:
  title: Letta Admin Blocks API
  version: 1.0.0
  description: REST API for Letta, the stateful agents platform. Manage agents, memory blocks, archival passages, sources, custom tools, MCP servers, multi-agent groups, runs, and streaming responses. Available as Letta Cloud (managed) at https://api.letta.com/v1 and as the self-hosted open-source server (Apache-2.0) typically run at http://localhost:8283.
  contact:
    name: Letta
    url: https://www.letta.com/
    email: support@letta.com
  license:
    name: Apache-2.0
    url: https://github.com/letta-ai/letta/blob/main/LICENSE
  x-logo:
    url: https://www.letta.com/favicon.ico
servers:
- url: https://api.letta.com
  description: Letta Cloud (managed)
- url: https://app.letta.com
  description: Letta Cloud (app)
- url: http://localhost:8283
  description: Self-hosted Letta server
security:
- bearerAuth: []
tags:
- name: Blocks
  description: Manage in-context memory blocks (core memory) shared across agents.
paths:
  /v1/blocks/:
    get:
      tags:
      - Blocks
      summary: List Blocks
      operationId: list_blocks
      parameters:
      - name: label
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            minLength: 1
            maxLength: 50
            pattern: ^[a-zA-Z0-9_/-]+$
          - type: 'null'
          description: Label to include (alphanumeric, hyphens, underscores, forward slashes)
          examples:
          - human
          - persona
          - the_label_of-a-block
          - the_label_of-a-block/with-forward-slash
          title: Label
        description: Label to include (alphanumeric, hyphens, underscores, forward slashes)
      - name: templates_only
        in: query
        required: false
        schema:
          type: boolean
          description: Whether to include only templates
          default: false
          title: Templates Only
        description: Whether to include only templates
      - name: name
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            minLength: 1
            maxLength: 100
            pattern: ^[a-zA-Z0-9 _-]+$
          - type: 'null'
          description: Name filter (alphanumeric, spaces, hyphens, underscores)
          examples:
          - My Agent
          - test_tool
          - default-config
          title: Name
        description: Name filter (alphanumeric, spaces, hyphens, underscores)
      - name: identity_id
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            minLength: 45
            maxLength: 45
            pattern: ^identity-[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
          - type: 'null'
          description: The ID of the identity in the format 'identity-<uuid4>'
          examples:
          - identity-123e4567-e89b-42d3-8456-426614174000
          title: Identity Id
        description: The ID of the identity in the format 'identity-<uuid4>'
      - name: identifier_keys
        in: query
        required: false
        schema:
          anyOf:
          - type: array
            items:
              type: string
          - type: 'null'
          description: Search agents by identifier keys
          title: Identifier Keys
        description: Search agents by identifier keys
      - name: project_id
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          description: Search blocks by project id
          title: Project Id
        description: Search blocks by project id
      - name: tags
        in: query
        required: false
        schema:
          anyOf:
          - type: array
            items:
              type: string
          - type: 'null'
          description: List of tags to filter blocks by
          title: Tags
        description: List of tags to filter blocks by
      - name: match_all_tags
        in: query
        required: false
        schema:
          type: boolean
          description: If True, only returns blocks that match ALL given tags. Otherwise, return blocks that have ANY of the passed-in tags.
          default: false
          title: Match All Tags
        description: If True, only returns blocks that match ALL given tags. Otherwise, return blocks that have ANY of the passed-in tags.
      - name: limit
        in: query
        required: false
        schema:
          anyOf:
          - type: integer
          - type: 'null'
          description: Number of blocks to return
          default: 50
          title: Limit
        description: Number of blocks to return
      - name: before
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          description: Block ID cursor for pagination. Returns blocks that come before this block ID in the specified sort order
          title: Before
        description: Block ID cursor for pagination. Returns blocks that come before this block ID in the specified sort order
      - name: after
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          description: Block ID cursor for pagination. Returns blocks that come after this block ID in the specified sort order
          title: After
        description: Block ID cursor for pagination. Returns blocks that come after this block ID in the specified sort order
      - name: order
        in: query
        required: false
        schema:
          enum:
          - asc
          - desc
          type: string
          description: Sort order for blocks by creation time. 'asc' for oldest first, 'desc' for newest first
          default: asc
          title: Order
        description: Sort order for blocks by creation time. 'asc' for oldest first, 'desc' for newest first
      - name: order_by
        in: query
        required: false
        schema:
          const: created_at
          type: string
          description: Field to sort by
          default: created_at
          title: Order By
        description: Field to sort by
      - name: label_search
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            minLength: 1
            maxLength: 50
            pattern: ^[a-zA-Z0-9_/-]+$
          - type: 'null'
          description: Search blocks by label. If provided, returns blocks whose label matches the search query. This is a full-text search on block labels.
          examples:
          - human
          - persona
          - the_label_of-a-block
          - the_label_of-a-block/with-forward-slash
          title: Label Search
        description: Search blocks by label. If provided, returns blocks whose label matches the search query. This is a full-text search on block labels.
      - name: description_search
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            minLength: 1
            maxLength: 200
          - type: 'null'
          description: Search blocks by description. If provided, returns blocks whose description matches the search query. This is a full-text search on block descriptions.
          title: Description Search
        description: Search blocks by description. If provided, returns blocks whose description matches the search query. This is a full-text search on block descriptions.
      - name: value_search
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            minLength: 1
            maxLength: 200
          - type: 'null'
          description: Search blocks by value. If provided, returns blocks whose value matches the search query. This is a full-text search on block values.
          title: Value Search
        description: Search blocks by value. If provided, returns blocks whose value matches the search query. This is a full-text search on block values.
      - name: connected_to_agents_count_gt
        in: query
        required: false
        schema:
          anyOf:
          - type: integer
          - type: 'null'
          description: Filter blocks by the number of connected agents. If provided, returns blocks that have more than this number of connected agents.
          title: Connected To Agents Count Gt
        description: Filter blocks by the number of connected agents. If provided, returns blocks that have more than this number of connected agents.
      - name: connected_to_agents_count_lt
        in: query
        required: false
        schema:
          anyOf:
          - type: integer
          - type: 'null'
          description: Filter blocks by the number of connected agents. If provided, returns blocks that have less than this number of connected agents.
          title: Connected To Agents Count Lt
        description: Filter blocks by the number of connected agents. If provided, returns blocks that have less than this number of connected agents.
      - name: connected_to_agents_count_eq
        in: query
        required: false
        schema:
          anyOf:
          - type: array
            items:
              type: integer
          - type: 'null'
          description: Filter blocks by the exact number of connected agents. If provided, returns blocks that have exactly this number of connected agents.
          title: Connected To Agents Count Eq
        description: Filter blocks by the exact number of connected agents. If provided, returns blocks that have exactly this number of connected agents.
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/BlockResponse'
                title: Response List Blocks
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
    post:
      tags:
      - Blocks
      summary: Create Block
      operationId: create_block
      parameters: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateBlock'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BlockResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
  /v1/blocks/count:
    get:
      tags:
      - Blocks
      summary: Count Blocks
      description: 'Count all blocks with optional filtering.

        Supports the same filters as list_blocks for consistent querying.'
      operationId: count_blocks
      parameters:
      - name: label
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            minLength: 1
            maxLength: 50
            pattern: ^[a-zA-Z0-9_/-]+$
          - type: 'null'
          description: Label to include (alphanumeric, hyphens, underscores, forward slashes)
          examples:
          - human
          - persona
          - the_label_of-a-block
          - the_label_of-a-block/with-forward-slash
          title: Label
        description: Label to include (alphanumeric, hyphens, underscores, forward slashes)
      - name: templates_only
        in: query
        required: false
        schema:
          type: boolean
          description: Whether to include only templates
          default: false
          title: Templates Only
        description: Whether to include only templates
      - name: name
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            minLength: 1
            maxLength: 100
            pattern: ^[a-zA-Z0-9 _-]+$
          - type: 'null'
          description: Name filter (alphanumeric, spaces, hyphens, underscores)
          examples:
          - My Agent
          - test_tool
          - default-config
          title: Name
        description: Name filter (alphanumeric, spaces, hyphens, underscores)
      - name: tags
        in: query
        required: false
        schema:
          anyOf:
          - type: array
            items:
              type: string
          - type: 'null'
          description: List of tags to filter blocks by
          title: Tags
        description: List of tags to filter blocks by
      - name: match_all_tags
        in: query
        required: false
        schema:
          type: boolean
          description: If True, only counts blocks that match ALL given tags. Otherwise, counts blocks that have ANY of the passed-in tags.
          default: false
          title: Match All Tags
        description: If True, only counts blocks that match ALL given tags. Otherwise, counts blocks that have ANY of the passed-in tags.
      - name: project_id
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          description: Search blocks by project id
          title: Project Id
        description: Search blocks by project id
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                type: integer
                title: Response Count Blocks
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
  /v1/blocks/{block_id}:
    patch:
      tags:
      - Blocks
      summary: Modify Block
      operationId: modify_block
      parameters:
      - name: block_id
        in: path
        required: true
        schema:
          type: string
          minLength: 42
          maxLength: 42
          pattern: ^block-[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
          description: The ID of the block in the format 'block-<uuid4>'
          examples:
          - block-123e4567-e89b-42d3-8456-426614174000
          title: Block Id
        description: The ID of the block in the format 'block-<uuid4>'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/BlockUpdate'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BlockResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
    delete:
      tags:
      - Blocks
      summary: Delete Block
      operationId: delete_block
      parameters:
      - name: block_id
        in: path
        required: true
        schema:
          type: string
          minLength: 42
          maxLength: 42
          pattern: ^block-[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
          description: The ID of the block in the format 'block-<uuid4>'
          examples:
          - block-123e4567-e89b-42d3-8456-426614174000
          title: Block Id
        description: The ID of the block in the format 'block-<uuid4>'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
    get:
      tags:
      - Blocks
      summary: Retrieve Block
      operationId: retrieve_block
      parameters:
      - name: block_id
        in: path
        required: true
        schema:
          type: string
          minLength: 42
          maxLength: 42
          pattern: ^block-[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
          description: The ID of the block in the format 'block-<uuid4>'
          examples:
          - block-123e4567-e89b-42d3-8456-426614174000
          title: Block Id
        description: The ID of the block in the format 'block-<uuid4>'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BlockResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
  /v1/blocks/{block_id}/agents:
    get:
      tags:
      - Blocks
      summary: List Agents for Block
      description: 'Retrieves all agents associated with the specified block.

        Raises a 404 if the block does not exist.'
      operationId: list_agents_for_block
      parameters:
      - name: block_id
        in: path
        required: true
        schema:
          type: string
          minLength: 42
          maxLength: 42
          pattern: ^block-[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
          description: The ID of the block in the format 'block-<uuid4>'
          examples:
          - block-123e4567-e89b-42d3-8456-426614174000
          title: Block Id
        description: The ID of the block in the format 'block-<uuid4>'
      - name: before
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          description: Agent ID cursor for pagination. Returns agents that come before this agent ID in the specified sort order
          title: Before
        description: Agent ID cursor for pagination. Returns agents that come before this agent ID in the specified sort order
      - name: after
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          description: Agent ID cursor for pagination. Returns agents that come after this agent ID in the specified sort order
          title: After
        description: Agent ID cursor for pagination. Returns agents that come after this agent ID in the specified sort order
      - name: limit
        in: query
        required: false
        schema:
          anyOf:
          - type: integer
          - type: 'null'
          description: Maximum number of agents to return
          default: 50
          title: Limit
        description: Maximum number of agents to return
      - name: order
        in: query
        required: false
        schema:
          enum:
          - asc
          - desc
          type: string
          description: Sort order for agents by creation time. 'asc' for oldest first, 'desc' for newest first
          default: desc
          title: Order
        description: Sort order for agents by creation time. 'asc' for oldest first, 'desc' for newest first
      - name: order_by
        in: query
        required: false
        schema:
          const: created_at
          type: string
          description: Field to sort by
          default: created_at
          title: Order By
        description: Field to sort by
      - name: include_relationships
        in: query
        required: false
        schema:
          anyOf:
          - type: array
            items:
              type: string
          - type: 'null'
          description: Specify which relational fields (e.g., 'tools', 'sources', 'memory') to include in the response. If not provided, all relationships are loaded by default. Using this can optimize performance by reducing unnecessary joins.This is a legacy parameter, and no longer supported after 1.0.0 SDK versions.
          deprecated: true
          title: Include Relationships
        description: Specify which relational fields (e.g., 'tools', 'sources', 'memory') to include in the response. If not provided, all relationships are loaded by default. Using this can optimize performance by reducing unnecessary joins.This is a legacy parameter, and no longer supported after 1.0.0 SDK versions.
        deprecated: true
      - name: include
        in: query
        required: false
        schema:
          type: array
          items:
            enum:
            - agent.blocks
            - agent.identities
            - agent.managed_group
            - agent.pending_approval
            - agent.secrets
            - agent.sources
            - agent.tags
            - agent.tools
            type: string
          description: Specify which relational fields to include in the response. No relationships are included by default.
          default: []
          title: Include
        description: Specify which relational fields to include in the response. No relationships are included by default.
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/AgentState'
                title: Response List Agents For Block
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
  /v1/blocks/{block_id}/identities/attach/{identity_id}:
    patch:
      tags:
      - Blocks
      summary: Attach Identity to Block
      description: Attach an identity to a block.
      operationId: attach_identity_to_block
      parameters:
      - name: identity_id
        in: path
        required: true
        schema:
          type: string
          title: Identity Id
      - name: block_id
        in: path
        required: true
        schema:
          type: string
          minLength: 42
          maxLength: 42
          pattern: ^block-[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
          description: The ID of the block in the format 'block-<uuid4>'
          examples:
          - block-123e4567-e89b-42d3-8456-426614174000
          title: Block Id
        description: The ID of the block in the format 'block-<uuid4>'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BlockResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
  /v1/blocks/{block_id}/identities/detach/{identity_id}:
    patch:
      tags:
      - Blocks
      summary: Detach Identity from Block
      description: Detach an identity from a block.
      operationId: detach_identity_from_block
      parameters:
      - name: identity_id
        in: path
        required: true
        schema:
          type: string
          title: Identity Id
      - name: block_id
        in: path
        required: true
        schema:
          type: string
          minLength: 42
          maxLength: 42
          pattern: ^block-[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
          description: The ID of the block in the format 'block-<uuid4>'
          examples:
          - block-123e4567-e89b-42d3-8456-426614174000
          title: Block Id
        description: The ID of the block in the format 'block-<uuid4>'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BlockResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
components:
  schemas:
    ZAIThinking:
      properties:
        type:
          type: string
          enum:
          - enabled
          - disabled
          title: Type
          description: Whether thinking is enabled or disabled.
          default: enabled
        clear_thinking:
          type: boolean
          title: Clear Thinking
          description: If False, preserved thinking is used (recommended for agents).
          default: false
      type: object
      title: ZAIThinking
      description: Thinking configuration for ZAI GLM-4.5+ models.
    FileBlock:
      properties:
        value:
          type: string
          title: Value
          description: Value of the block.
        limit:
          type: integer
          title: Limit
          description: Character limit of the block.
          default: 100000
        project_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Project Id
          description: The associated project id.
        template_name:
          anyOf:
          - type: string
          - type: 'null'
          title: Template Name
          description: Name of the block if it is a template.
        is_template:
          type: boolean
          title: Is Template
          description: Whether the block is a template (e.g. saved human/persona options).
          default: false
        template_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Template Id
          description: The id of the template.
        base_template_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Base Template Id
          description: The base template id of the block.
        deployment_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Deployment Id
          description: The id of the deployment.
        entity_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Entity Id
          description: The id of the entity within the template.
        preserve_on_migration:
          anyOf:
          - type: boolean
          - type: 'null'
          title: Preserve On Migration
          description: Preserve the block on template migration.
          default: false
        label:
          anyOf:
          - type: string
          - type: 'null'
          title: Label
          description: Label of the block (e.g. 'human', 'persona') in the context window.
        read_only:
          type: boolean
          title: Read Only
          description: Whether the agent has read-only access to the block.
          default: false
        description:
          anyOf:
          - type: string
          - type: 'null'
          title: Description
          description: Description of the block.
        metadata:
          anyOf:
          - additionalProperties: true
            type: object
          - type: 'null'
          title: Metadata
          description: Metadata of the block.
          default: {}
        hidden:
          anyOf:
          - type: boolean
          - type: 'null'
          title: Hidden
          description: If set to True, the block will be hidden.
        id:
          type: string
          pattern: ^block-[a-fA-F0-9]{8}
          title: Id
          description: The human-friendly ID of the Block
          examples:
          - block-123e4567-e89b-12d3-a456-426614174000
        created_by_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Created By Id
          description: The id of the user that made this Block.
        last_updated_by_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Last Updated By Id
          description: The id of the user that last updated this Block.
        tags:
          anyOf:
          - items:
              type: string
            type: array
          - type: 'null'
          title: Tags
          description: The tags associated with the block.
          default: []
        file_id:
          type: string
          title: File Id
          description: Unique identifier of the file.
        source_id:
          type: string
          title: Source Id
          description: 'Deprecated: Use `folder_id` field instead. Unique identifier of the source.'
          deprecated: true
        is_open:
          type: boolean
          title: Is Open
          description: True if the agent currently has the file open.
        last_accessed_at:
          anyOf:
          - type: string
            format: date-time
          - type: 'null'
          title: Last Accessed At
          description: UTC timestamp of the agent’s most recent access to this file. Any operations from the open, close, or search tools will update this field.
      type: object
      required:
      - value
      - file_id
      - source_id
      - is_open
      title: FileBlock
    AgentState:
      properties:
        created_by_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Created By Id
          description: The id of the user that made this object.
        last_updated_by_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Last Updated By Id
          description: The id of the user that made this object.
        created_at:
          anyOf:
          - type: string
            format: date-time
          - type: 'null'
          title: Created At
          description: The timestamp when the object was created.
        updated_at:
          anyOf:
          - type: string
            format: date-time
          - type: 'null'
          title: Updated At
          description: The timestamp when the object was last updated.
        id:
          type: string
          title: Id
          description: The id of the agent. Assigned by the database.
        name:
          type: string
          title: Name
          description: The name of the agent.
        tool_rules:
          anyOf:
          - items:
              oneOf:
              - $ref: '#/components/schemas/ChildToolRule'
              - $ref: '#/components/schemas/InitToolRule'
              - $ref: '#/components/schemas/TerminalToolRule'
              - $ref: '#/components/schemas/ConditionalToolRule'
              - $ref: '#/components/schemas/ContinueToolRule'
              - $ref: '#/components/schemas/RequiredBeforeExitToolRule'
              - $ref: '#/components/schemas/MaxCountPerStepToolRule'
              - $ref: '#/components/schemas/ParentToolRule'
              - $ref: '#/components/schemas/RequiresApprovalToolRule'
              discriminator:
                propertyName: type
                mapping:
                  conditional: '#/components/schemas/ConditionalToolRule'
                  constrain_child_tools: '#/components/schemas/ChildToolRule'
                  continue_loop: '#/components/schemas/ContinueToolRule'
                  exit_loop: '#/components/schemas/TerminalToolRule'
                  max_count_per_step: '#/components/schemas/MaxCountPerStepToolRule'
                  parent_last_tool: '#/components/schemas/ParentToolRule'
                  required_before_exit: '#/components/schemas/RequiredBeforeExitToolRule'
                  requires_approval: '#/components/schemas/RequiresApprovalToolRule'
                  run_first: '#/components/schemas/InitToolRule'
            type: array
          - type: 'null'
          title: Tool Rules
          description: The list of tool rules.
        message_ids:
          anyOf:
          - items:
              type: string
            type: array
          - type: 'null'
          title: Message Ids
          description: The ids of the messages in the agent's in-context memory.
        system:
          type: string
          title: System
          description: The system prompt used by the agent.
        agent_type:
          $ref: '#/components/schemas/AgentType'
          description: The type of agent.
        llm_config:
          $ref: '#/components/schemas/LLMConfig'
          description: 'Deprecated: Use `model` field instead. The LLM configuration used by the agent.'
          deprecated: true
        embedding_config

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# Full source: https://raw.githubusercontent.com/api-evangelist/letta/refs/heads/main/openapi/letta-blocks-api-openapi.yml