chore: remove unused runtime dependencies (10 -> 4) - #346
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…f injecting an arbitrary type
## Problem
For a request body field typed as a union of two real types (e.g. `dict[str, list[str]] | list[str]`), the projected MCP tool schema gets a single arbitrary `"type"` injected alongside `anyOf`. The MCP server's jsonschema validator then enforces that `"type"` strictly and rejects every call using the variant that lost the pick, with a misleading error like:
```
Input validation error: {'Skills': [...]} is not of type 'array'
```
The injected type is also non-deterministic (`next(iter(set))`), so which variant breaks can differ per run. Fixes tadata-org#307.
## Root cause
In `convert_openapi_to_mcp_tools`, both the query-param and body-param loops do:
```python
if "type" not in properties[param_name]:
properties[param_name]["type"] = get_single_param_type_from_schema(param_schema)
```
For `T | U` (both real types) Pydantic emits `{"anyOf": [...]}` with no top-level `"type"`, so the branch fires and one arbitrary variant type wins.
## Fix
Only fall back to `get_single_param_type_from_schema` when the union has at most one non-null variant. `T | None` (nullable) keeps the existing collapse behavior — its existing tests still pass unchanged — while `T | U` keeps `anyOf` verbatim, which the JSON Schema validator at the MCP layer handles correctly.
## Verification
- New test `test_union_type_schema_not_collapsed` asserts `anyOf` is preserved with no injected `"type"` and both `object`/`array` variants present.
- Repro from the issue validated with `jsonschema`: both the dict variant and the list variant pass validation (previously one of them always failed).
- Full suite: 70 passed (the 20 `test_sse_real_transport` errors are the pre-existing Windows `os.fork` limitation tracked in tadata-org#332).
The package itself imports none of these: - typer, rich: never referenced anywhere in fastapi_mcp/ - requests: zero imports (httpx is used everywhere) - tomli: zero imports - pydantic-settings: zero imports (mcp already depends on it anyway) - uvicorn: not needed at runtime (mcp itself pulls it for its own transports); kept as a 'deploy' extra and in the dev group for the real-transport tests and the examples Runtime deps go from 10 to 4: fastapi, mcp, pydantic, httpx. Verified: 78/78 tests, ruff clean, mypy clean, wheel metadata confirmed.
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Problem
The library declares 10 runtime dependencies, but several are never imported by the package itself. This adds install weight and friction for downstream adopters (raised in #275 —
richin particular impacts log output configuration of host apps).Audit results
fastapi_mcp/server.py,auth/proxy.pymcpitself pulls it for its own transportsdeployextra + dev groupRuntime dependencies go from 10 to 4.
Notes
uvicornremains reachable:pip install fastapi-mcp[deploy], and the dev dependency group keeps it fortests/test_http_real_transport.py/tests/test_sse_real_transport.py.uv.lockregenerated; typer/rich/requests/urllib3/pygments/shellingham and friends drop out of the resolved graph entirely.fastapi,httpx,mcp,pydantic(+uvicorn; extra == 'deploy').Verification
uv run pytest tests/: 78 passed (real-transportos.forkerrors are the pre-existing Windows limitation tracked in test: skip real-transport tests on Windows (they require os.fork) #332, identical on unpatched main).uv run ruff check fastapi_mcp+ruff format --check: clean.uv run mypy fastapi_mcp: no issues in 12 source files.uv build+ METADATA inspection of the built wheel.Fixes #275