mcp-swagger

name	mcp-swagger
description	Generate runnable MCP servers from Swagger/OpenAPI specifications using the mcp-swagger-cli tool inside Docker. Use when the user wants to turn any REST API into an MCP server, integrate a third-party API into an agent workflow, or generate MCP tools from an OpenAPI/Swagger spec (JSON or YAML, local file or URL).
requires_bins	["docker"]

MCP Swagger — Docker ({{os}})

Generate runnable MCP servers from OpenAPI/Swagger specifications using the mcp-swagger-cli tool inside Docker.

Setup

Write the full install + generate flow as a single Python script via Filesystem MCP, then run it in one container execution:

# setup_and_generate.py
import subprocess, sys

# Install CLI from skill bundle
subprocess.run([sys.executable, "-m", "pip", "install", "-e", "/workspace/skills/bundled/mcp-swagger/scripts"], check=True)

# Verify
subprocess.run(["mcp-swagger", "--help"], check=True)

Run in Docker using the OS shell tool:

# Unix/Mac
docker run --rm \
  -v "{{paths.sandbox}}:/output" \
  -v "{{paths.base}}:/workspace" \
  "appropriate python container" python /workspace/setup_and_generate.py

# Windows
docker run --rm -v "{{paths.sandbox}}:/output" -v "{{paths.base}}:/workspace" "appropriate python container"-python python /workspace/setup_and_generate.py

Never use python -m mcp_swagger_cli — the package has no __main__.py. Always use the mcp-swagger entry point.

Finding a Spec

Priority order:

1. Official provider repo — search GitHub for <provider> openapi or <provider> swagger.
2. Provider developer docs — look for openapi.json or swagger.yaml. Common paths: /openapi.json, /api-docs, /swagger.json.
3. apis.guru — last resort. Specs here are often outdated. Always validate base URL before using.

Never use a spec without validating the base URL first.

Validation

Before generating, verify the spec's base URL resolves correctly:

mcp-swagger info "<spec-path-or-url>"
curl "<base-url><a-known-path>?<required-params>"

If curl returns a DNS error or 404, override with --base-url at generation time.

Generating a Server

Write the full install + generate flow as a single Python script, then execute in Docker. All output paths inside the script must use /output/.

Basic

subprocess.run([
    "mcp-swagger", "create", "<spec>",
    "-o", "/output/<server-name>",
    "--name", "<ServerName>"
], check=True)

With Base URL Override

subprocess.run([
    "mcp-swagger", "create", "<spec>",
    "-o", "/output/<server-name>",
    "--name", "<ServerName>",
    "--base-url", "https://correct-host.com"
], check=True)

With Header Auth

subprocess.run([
    "mcp-swagger", "create", "<spec>",
    "-o", "/output/<server-name>",
    "--name", "<ServerName>",
    "--api-key-env", "MY_API_KEY",
    "--api-key-header", "Authorization",
    "--api-key-prefix", "Bearer"
], check=True)

With Path Filtering (for large specs)

subprocess.run([
    "mcp-swagger", "create", "<spec>",
    "-o", "/output/<server-name>",
    "--name", "<ServerName>",
    "--path-filter", "/v1/charges",
    "--path-filter", "/v1/customers",
    "--path-filter", "/v1/payment_intents"
], check=True)

With Static Custom Headers

subprocess.run([
    "mcp-swagger", "create", "<spec>",
    "-o", "/output/<server-name>",
    "--name", "<ServerName>",
    "-H", "X-App-Id: abc123",
    "-H", "X-Version: 2"
], check=True)

Auth Patterns

API auth style	How to handle
Authorization: Bearer <token>	--api-key-env VAR --api-key-header Authorization --api-key-prefix Bearer
Authorization: Token <token>	--api-key-env VAR --api-key-header Authorization --api-key-prefix Token
Custom header (e.g. X-API-Key)	--api-key-env VAR --api-key-header X-API-Key --api-key-prefix ""
Query param (e.g. ?api_key=)	Pass key as tool argument, or manually wire env var in generated main.py
No auth	Omit all auth flags

After Generation

cd {{paths.sandbox}}/<server-name>
pip install -e .
<server-name>

Or with SSE:

<server-name> --sse 8000

Verifying the Generated Server

After generation, check BASE_URL matches the actual working host:

{{shell}} {{shell.flag}} "grep -n BASE_URL {{paths.sandbox}}/<server-name>/main.py"

If it doesn't match, regenerate with --base-url.

Connecting to Mux

Add to your config.json mcpServers:

{
  "<server-name>": {
    "type": "stdio",
    "command": "<server-name>",
    "args": [],
    "env": {
      "MY_API_KEY": "MY_API_KEY"
    },
    "enabled": true
  }
}

Known Pitfalls

• python -m mcp_swagger_cli fails — no __main__.py. Always use mcp-swagger entry point.
• DNS error (getaddrinfo failed) — base URL in spec is wrong. Override with --base-url.
• 401 Unauthorized — API key invalid or wrong env var name. Test key directly with curl first.
• 404 on all endpoints — spec paths missing a prefix. Override base URL to include the prefix.
• Large specs (Stripe, GitHub, etc.) — use --path-filter. Stripe uses default tag — --tag won't work, use --path-filter.
• Optional params causing validation errors — omit optional fields rather than passing null.
• Query param auth exposed as tool argument — manually edit main.py to read from os.environ.
• Spec from apis.guru — treat base URL as suspect. Always validate with curl before generating.