> ## Documentation Index > Fetch the complete documentation index at: https://docs.seamless.ai/llms.txt > Use this file to discover all available pages before exploring further. # MCP Transport > The single transport endpoint for all MCP communication. All tool calls, resource reads, and protocol messages are sent here as JSON-RPC 2.0 requests. This is a stateless endpoint — each request creates a fresh server instance scoped to the authenticated user. Every request must send `Content-Type: application/json` and an `Accept` header listing both `application/json` and `text/event-stream`; responses are always JSON. The body is a single JSON-RPC message or an array of them. Notifications (such as `notifications/initialized`) carry no `id` and receive an empty `202` response. ## OpenAPI ````yaml mcp-openapi.yaml POST /mcp openapi: 3.0.3 info: title: Seamless.AI MCP Server version: 1.0.0 description: > JSON-RPC 2.0 transport for the Seamless.AI [Model Context Protocol (MCP)](https://modelcontextprotocol.io/) server. See [MCP Docs](https://docs.seamless.ai/mcp/overview) for setup, [Authentication](https://docs.seamless.ai/mcp/authentication), and the [tool reference](https://docs.seamless.ai/mcp/tools/search). servers: - url: https://mcp.seamless.ai description: Production security: - OAuth2: - mcp.all - ApiKey: [] paths: /mcp: post: summary: MCP Transport description: > The single transport endpoint for all MCP communication. All tool calls, resource reads, and protocol messages are sent here as JSON-RPC 2.0 requests. This is a stateless endpoint — each request creates a fresh server instance scoped to the authenticated user. Every request must send `Content-Type: application/json` and an `Accept` header listing both `application/json` and `text/event-stream`; responses are always JSON. The body is a single JSON-RPC message or an array of them. Notifications (such as `notifications/initialized`) carry no `id` and receive an empty `202` response. operationId: mcp_transport parameters: - name: Accept in: header required: true schema: type: string example: application/json, text/event-stream description: Must include both `application/json` and `text/event-stream`. requestBody: required: true content: application/json: schema: type: object required: - jsonrpc - method properties: jsonrpc: type: string enum: - '2.0' description: JSON-RPC version. Always "2.0". method: type: string description: >- MCP method to invoke (e.g. "tools/list", "tools/call", "resources/read"). example: tools/call params: type: object description: >- Method-specific parameters. For `tools/call`, includes `name` (tool name) and `arguments` (tool input). For `resources/read`, includes `uri`. properties: name: type: string description: Tool name (for tools/call). example: search_contacts arguments: type: object description: Tool input arguments (for tools/call). additionalProperties: true uri: type: string description: Resource URI (for resources/read). example: seamless://credits id: oneOf: - type: string - type: integer description: >- Request ID for correlating responses. Omit it for notifications. examples: listTools: summary: List available tools value: jsonrpc: '2.0' method: tools/list params: {} id: 1 callTool: summary: Call a tool value: jsonrpc: '2.0' method: tools/call params: name: search_contacts arguments: companyName: - Acme Corp limit: 10 id: 2 readResource: summary: Read a resource value: jsonrpc: '2.0' method: resources/read params: uri: seamless://credits id: 3 responses: '200': description: JSON-RPC 2.0 response with the result or error. content: application/json: schema: type: object properties: jsonrpc: type: string example: '2.0' result: description: >- Method-specific result payload. `tools/call` responses match `McpToolCallResult`. anyOf: - $ref: '#/components/schemas/McpToolCallResult' - type: object additionalProperties: true error: type: object description: >- JSON-RPC protocol error, such as an unknown method. Tool failures are returned in `result` with `isError` set to true. properties: code: type: integer message: type: string id: oneOf: - type: string - type: integer examples: listToolsResult: summary: tools/list response (read tool with outputSchema) value: jsonrpc: '2.0' result: tools: - name: search_contacts description: >- Search the Seamless.AI database for contacts matching filters like company, title, seniority, and location. (Abbreviated; the generated Search tools page has the full text.) inputSchema: type: object properties: companyName: type: array items: type: string outputSchema: type: object required: - results properties: results: type: array items: type: object additionalProperties: true pagination: type: object additionalProperties: true annotations: readOnlyHint: true destructiveHint: false idempotentHint: true openWorldHint: true id: 1 toolResult: summary: Successful read tool call (text + structuredContent) value: jsonrpc: '2.0' result: content: - type: text text: > Results (2): searchResultId | firstName | lastName | jobTitle | companyName --- | --- | --- | --- | --- 708dbb34-3849-3c06-abd1-238b9a0295b3 | Taylor | Gonsalves | Customer Success Manager | Seamless a1b2c3d4-5678-90ab-cdef-1234567890ab | Alex | Rivera | VP Sales | Acme Corp Pagination: total: 15, nextToken: eyJwYWdlIjoyfQ==, creditsConsumed: 1, creditsRemaining: 999 structuredContent: results: - searchResultId: 708dbb34-3849-3c06-abd1-238b9a0295b3 firstName: Taylor lastName: Gonsalves fullName: Taylor Gonsalves name: Taylor Gonsalves jobTitle: Customer Success Manager title: Customer Success Manager companyName: Seamless company: Seamless - searchResultId: a1b2c3d4-5678-90ab-cdef-1234567890ab firstName: Alex lastName: Rivera fullName: Alex Rivera name: Alex Rivera jobTitle: VP Sales title: VP Sales companyName: Acme Corp company: Acme Corp pagination: total: 15 nextToken: eyJwYWdlIjoyfQ== creditsConsumed: 1 creditsRemaining: 999 id: 2 writeToolResult: summary: Successful write tool call (no outputSchema) value: jsonrpc: '2.0' result: content: - type: text text: |- { "id": 12345, "name": "VP Sales at SaaS" } structuredContent: id: 12345 name: VP Sales at SaaS id: 2 toolErrorResult: summary: Failed tool call (invalid arguments) value: jsonrpc: '2.0' result: content: - type: text text: >- MCP error -32602: Input validation error: Invalid arguments for tool search_contacts: Invalid input: expected array, received string at companyName isError: true id: 2 '202': description: >- Accepted. Returned with an empty body when the request contained only notifications or responses, with no JSON-RPC request to answer. '400': description: >- Malformed JSON or a body that is not a valid JSON-RPC message. The body is a JSON-RPC error (`-32700` or `-32600`). '401': description: >- Missing or invalid authentication. Includes a `WWW-Authenticate` header pointing at the protected resource metadata. '403': description: >- Authenticated, but not allowed. The token lacks the `mcp.all` scope, or MCP access is not enabled for the user or organization. '405': description: >- Method not allowed. GET (SSE streams) and DELETE (session teardown) are not supported by this stateless server. '406': description: >- The `Accept` header does not list both `application/json` and `text/event-stream`. '415': description: The `Content-Type` is not `application/json`. '422': description: >- The authenticated account has no public API access (`missingApiAccess`). '429': description: >- Rate limit exceeded. `X-RateLimit-Limit`, `X-RateLimit-Remaining`, and `X-RateLimit-Reset` describe the window. components: schemas: McpToolCallResult: type: object description: tools/call result payload. properties: content: type: array description: Human-readable text output. items: type: object required: - type - text properties: type: type: string enum: - text text: type: string structuredContent: description: >- Machine-readable output. Matches the tool's outputSchema when it publishes one; otherwise mirrors the text content with no guaranteed fields. type: object additionalProperties: true isError: type: boolean description: True when the tool failed; omitted on success. securitySchemes: OAuth2: type: oauth2 flows: authorizationCode: authorizationUrl: https://mcp.seamless.ai/mcp/authorize tokenUrl: https://mcp.seamless.ai/mcp/token scopes: mcp.all: Full MCP access ApiKey: type: apiKey name: Token in: header description: API key passed via the `Token` header. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.