> ## Documentation Index > Fetch the complete documentation index at: https://docs.eclatira.com/llms.txt > Use this file to discover all available pages before exploring further. # Attach an MCP server to an agent > Attaches a connected MCP server to an agent: its tools become callable the next time that agent's session is built (existing live sessions are unaffected until they reconnect/rebuild). By default every tool the server exposes is available; pass `enabled_tools` to restrict this agent to a subset (see V1AttachMcpServerRequest) — a tool left out is never declared to the model at all, not merely discouraged. Calling this again on an already-attached server updates its tool selection (`updated`) rather than being a no-op — the way to change which tools are enabled without detaching and reattaching. ## OpenAPI ````yaml /openapi.json post /api/v1/agents/{agent_id}/mcp-servers/attach/{mcp_server_id} openapi: 3.1.0 info: title: Eclatira API description: >- Programmatically create calls and batches, manage agents/tools/knowledge, and retrieve conversation analytics. contact: name: Eclatira Support email: contact@eclatira.com version: 1.0.0 servers: - url: https://app.eclatira.com description: API Server security: [] tags: - name: developer-api description: >- The API-key-authenticated developer surface: calls, batches, and agents. Authenticate with `Authorization: Bearer ek_...`. - name: Calls description: Place outbound calls with an agent, check status, list history. - name: Batches description: 'Outbound call campaigns: create, list, inspect, cancel, retry.' - name: Agents description: Create and manage the agents that place and receive calls. - name: Tools description: Custom actions an agent can call mid-call, attached per-agent. - name: MCP Servers description: >- Connect an agent to an external MCP (Model Context Protocol) server so it can call that server's tools, with static or OAuth auth. - name: Knowledge Base description: Upload files and index them into an agent's knowledge base. - name: Realtime description: >- Mint a short-lived session token to open a live voice/video WebSocket connection: the only supported way for an API-key holder to authenticate into /ws/{user_id}. - name: Webhooks description: >- Register a durable callback URL to receive call.completed and batch.completed events for every matching workspace event, and fetch the tenant signing secret used to verify X-Webhook-Signature. - name: developer-api-keys description: >- Account-management routes (create/list/revoke API keys), authenticated via dashboard login, not an API key, since they mint the credentials the rest of the developer API uses. paths: /api/v1/agents/{agent_id}/mcp-servers/attach/{mcp_server_id}: post: tags: - MCP Servers - developer-api summary: Attach an MCP server to an agent description: |- Attaches a connected MCP server to an agent: its tools become callable the next time that agent's session is built (existing live sessions are unaffected until they reconnect/rebuild). By default every tool the server exposes is available; pass `enabled_tools` to restrict this agent to a subset (see V1AttachMcpServerRequest) — a tool left out is never declared to the model at all, not merely discouraged. Calling this again on an already-attached server updates its tool selection (`updated`) rather than being a no-op — the way to change which tools are enabled without detaching and reattaching. operationId: attachMcpServer parameters: - name: agent_id in: path required: true schema: type: string title: Agent Id - name: mcp_server_id in: path required: true schema: type: string title: Mcp Server Id requestBody: content: application/json: schema: anyOf: - $ref: '#/components/schemas/V1AttachMcpServerRequest' - type: 'null' title: Body responses: '200': description: Successful Response content: application/json: schema: $ref: '#/components/schemas/V1AttachMcpServerResponse' '402': description: >- The tenant's billing status blocks attaching MCP servers (e.g. a past_due/unpaid subscription). content: application/json: schema: $ref: '#/components/schemas/V1ErrorResponse' '403': description: The agent or MCP server exists, but belongs to a different tenant. content: application/json: schema: $ref: '#/components/schemas/V1ErrorResponse' '404': description: >- No agent exists with this `agent_id`, or no MCP server exists with this `mcp_server_id`. content: application/json: schema: $ref: '#/components/schemas/V1ErrorResponse' '422': description: Validation Error content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' security: - ApiKeyAuth: [] components: schemas: V1AttachMcpServerRequest: properties: enabled_tools: anyOf: - items: type: string type: array - type: 'null' title: Enabled Tools additionalProperties: false type: object title: V1AttachMcpServerRequest description: |- Body is entirely optional — an empty/absent body means every tool the server exposes is available to this agent (the pre-existing behavior). Calling attach again on an already-attached server updates its tool selection rather than being a no-op, so a dev can change which tools are enabled without detaching and reattaching. V1AttachMcpServerResponse: properties: status: type: string title: Status enabled_tools: anyOf: - items: type: string type: array - type: 'null' title: Enabled Tools type: object required: - status title: V1AttachMcpServerResponse V1ErrorResponse: properties: error: $ref: '#/components/schemas/V1ErrorDetail' type: object required: - error title: V1ErrorResponse description: |- The error envelope every `developer-api`-tagged route returns for non-2xx responses, including `422`; this overrides FastAPI's default validation-error shape. HTTPValidationError: properties: detail: items: $ref: '#/components/schemas/ValidationError' type: array title: Detail type: object title: HTTPValidationError V1ErrorDetail: properties: type: type: string title: Type code: type: string title: Code message: type: string title: Message param: anyOf: - type: string - type: 'null' title: Param request_id: anyOf: - type: string - type: 'null' title: Request Id type: object required: - type - code - message title: V1ErrorDetail ValidationError: properties: loc: items: anyOf: - type: string - type: integer type: array title: Location msg: type: string title: Message type: type: string title: Error Type input: title: Input ctx: type: object title: Context type: object required: - loc - msg - type title: ValidationError securitySchemes: ApiKeyAuth: type: http scheme: bearer description: >- A long-lived, privileged API key (`ek_...` prefix), minted once from the dashboard. Intended for trusted server-side use only; never expose it in client-side code. Send as `Authorization: Bearer ek_...`. Required by every Calls, Batches, Agents, Tools, MCP Servers, Documents, and Realtime route. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.