mcp-server-openapi
Provides an MCP server that reads an OpenAPI 3.0/3.1 specification (JSON) and dynamically generates MCP tools for each API endpoint/method. When called by an MCP client (e.g., Claude Desktop), it validates parameters, constructs the HTTP request (including path/query/header/body), applies an optional configured Authorization header, and returns formatted JSON responses with errors.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
README claims a 30-second timeout and 'Detailed error messages without exposing sensitive data' plus parameter validation and URL/header escaping. However, there is no provided evidence for TLS enforcement details, secure secret storage/logging behavior, dependency audit status, or defense against SSRF/path traversal via OpenAPI-defined URLs.
⚡ Reliability
Best When
You have a reasonably complete OpenAPI JSON spec for a REST API and can authenticate using a static header value (Bearer/API key/custom header) configured at startup.
Avoid When
Your OpenAPI specs are incomplete/incorrect (e.g., missing operationId, parameter schemas) or you need OAuth2 flows, pagination semantics, retries/idempotency guarantees, and comprehensive rate-limit handling documented by the server.
Use Cases
- • Expose any REST API described by an OpenAPI spec as MCP tools for an LLM assistant
- • Rapidly integrate internal or third-party REST APIs into Claude Desktop via MCP
- • Generate tool schemas and argument validation automatically from OpenAPI
- • Provide a generic “API caller” interface for agents without writing bespoke tool wrappers
Not For
- • APIs that require complex auth flows not representable as a single static header/token
- • Non-REST or non-OpenAPI-described functionality (e.g., custom RPC protocols, streaming-only APIs)
- • Production deployments where you need a fully specified, reviewed MCP server contract, test coverage evidence, and explicit operational SLAs
Interface
Authentication
Auth appears to be passed as a single configured header value; there is no indication of OAuth2 or fine-grained scope enforcement.
Pricing
No pricing information provided; this appears to be an open-source/self-hosted MCP server.
Agent Metadata
Known Gotchas
- ⚠ Tool names depend on operationId; missing/duplicate operationId may lead to less stable/less predictable tool naming.
- ⚠ The server accepts OpenAPI JSON only (YAML not supported), so specs may need conversion.
- ⚠ Static header auth (-auth) may not work for APIs requiring OAuth2 token exchange/refresh flows.
- ⚠ Rate limiting behavior is not documented; agents may need to implement backoff outside the MCP layer.
- ⚠ Spec completeness matters: incorrect parameter schemas or missing required fields can cause tool call failures.
Alternatives
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Scores are editorial opinions as of 2026-04-04.