> ## Documentation Index > Fetch the complete documentation index at: https://docs.enkryptai.com/llms.txt > Use this file to discover all available pages before exploring further. # Call MCP Server Tool > Executes a tool call on an MCP server — the playground API for testing and debugging tools by directly invoking them with parameters. The target server is identified by the `X-Enkrypt-MCP-Registry-Server` header — the gateway fetches its config from `GET /mcp-registry/get-server` using your `apikey` and uses the cloud's 200/401/403 response as the authentication gate. The request body carries the tool invocation: `tool_name` (required) and optional `tool_arguments`. ## OpenAPI ````yaml POST /mcp-playground/call-tool openapi: 3.0.0 info: title: Enkrypt AI APIs version: 2.0.0 servers: - url: https://api.enkryptai.com security: - apiKeyAuth: [] tags: - name: Guardrails - name: Code of Conduct - name: Endpoints - name: Datasets - name: Redteam - name: Deployments - name: AI Proxy - name: Leaderboard - name: Archived - name: MCP Hub description: >- MCP Hub vulnerability scanning APIs. Submitting scans (the POST endpoints) is open to all authenticated callers. The scan **retrieval** APIs — Get Scan Job Status, Get Complete Scan Results, List Scans, and Get MCP Hub Scan Statistics (the GET endpoints) — are an **enterprise data-license feature**: they require your organization to have MCP Hub API access enabled by Enkrypt, otherwise they return `403`. Contact us at support@enkryptai.com to enable access. - name: MCP Registry Servers - name: MCP Gateways - name: MCP Playground paths: /mcp-playground/call-tool: post: tags: - MCP Playground summary: Call MCP Server Tool description: >- Executes a tool call on an MCP server — the playground API for testing and debugging tools by directly invoking them with parameters. The target server is identified by the `X-Enkrypt-MCP-Registry-Server` header — the gateway fetches its config from `GET /mcp-registry/get-server` using your `apikey` and uses the cloud's 200/401/403 response as the authentication gate. The request body carries the tool invocation: `tool_name` (required) and optional `tool_arguments`. operationId: callMCPTool parameters: - $ref: '#/components/parameters/MCPGatewayRegistryServerHeader' - $ref: '#/components/parameters/MCPGatewayRegistryServerVersionHeader' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/MCPGatewayCallToolRequest' examples: read-file: summary: Read a file value: tool_name: read_file tool_arguments: path: /tmp/test.txt write-file: summary: Write to a file value: tool_name: write_file tool_arguments: path: /tmp/output.txt content: Hello, World! responses: '200': description: Tool executed successfully content: application/json: schema: $ref: '#/components/schemas/MCPGatewayCallToolResponse' '400': $ref: '#/components/responses/MCPGatewayBadRequest' '401': $ref: '#/components/responses/MCPGatewayUnauthorized' '403': $ref: '#/components/responses/MCPGatewayForbidden' '404': $ref: '#/components/responses/MCPGatewayNotFound' '429': description: Resource limit exceeded content: application/json: schema: $ref: '#/components/schemas/MCPGatewayErrorResponse' '500': $ref: '#/components/responses/MCPGatewayInternalError' servers: - url: https://mcp.enkryptai.com components: parameters: MCPGatewayRegistryServerHeader: name: X-Enkrypt-MCP-Registry-Server in: header required: true description: Registry server saved_name schema: type: string maxLength: 32 example: my-filesystem-server MCPGatewayRegistryServerVersionHeader: name: X-Enkrypt-MCP-Registry-Server-Version in: header required: false description: Registry server version (defaults to "v1") schema: type: string default: v1 example: v1 schemas: MCPGatewayCallToolRequest: type: object required: - tool_name properties: tool_name: type: string description: Name of the tool to call example: read_file tool_arguments: type: object additionalProperties: true description: Arguments to pass to the tool (max 100KB, max depth 10 levels) MCPGatewayCallToolResponse: type: object properties: success: type: boolean description: Whether the tool call was successful error: type: string nullable: true description: Error message if failed details: type: string nullable: true description: Additional error details data: type: object properties: saved_name: type: string description: Registry server name server_version: type: string description: Server version server_name: type: string nullable: true description: MCP server package name description: type: string nullable: true description: Server description tool_name: type: string description: Name of the tool that was called tool_arguments: type: object additionalProperties: true description: Arguments that were passed to the tool result: type: object description: Result from the tool execution properties: content: type: array description: Content returned by the tool items: type: object properties: type: type: string description: Content type (e.g., text, image) text: type: string nullable: true description: Text content data: type: string nullable: true description: Base64-encoded data for non-text content mimeType: type: string nullable: true description: MIME type for non-text content isError: type: boolean description: Whether the tool execution resulted in an error executed_at: type: string format: date-time description: Timestamp when the tool was executed MCPGatewayErrorResponse: type: object required: - error properties: error: type: string description: Error message responses: MCPGatewayBadRequest: description: Bad request - invalid input content: application/json: schema: $ref: '#/components/schemas/MCPGatewayErrorResponse' MCPGatewayUnauthorized: description: Unauthorized - invalid or missing API key content: application/json: schema: $ref: '#/components/schemas/MCPGatewayErrorResponse' MCPGatewayForbidden: description: Forbidden - insufficient permissions content: application/json: schema: $ref: '#/components/schemas/MCPGatewayErrorResponse' MCPGatewayNotFound: description: Resource not found content: application/json: schema: $ref: '#/components/schemas/MCPGatewayErrorResponse' MCPGatewayInternalError: description: Internal server error content: application/json: schema: $ref: '#/components/schemas/MCPGatewayErrorResponse' securitySchemes: apiKeyAuth: type: apiKey in: header name: apikey ````