feat(cli): support env vars in mcp dev (#339)#2506
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GitAashishG wants to merge 2 commits intomodelcontextprotocol:mainfrom
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feat(cli): support env vars in mcp dev (#339)#2506GitAashishG wants to merge 2 commits intomodelcontextprotocol:mainfrom
mcp dev (#339)#2506GitAashishG wants to merge 2 commits intomodelcontextprotocol:mainfrom
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Add `--env-var/-v` and `--env-file/-f` options to the `mcp dev` command so the inspector subprocess inherits caller-provided environment variables — mirroring what `mcp install` already accepts. Inline `-v` flags override values loaded from `--env-file`. Extract the shared resolution logic into `_resolve_env` and refactor `mcp install` to use it (no behavior change). Document the new flags in README.v2.md and add unit tests for `_resolve_env`. Closes modelcontextprotocol#339
Add tests for the dotenv-missing, dotenv-raises, and malformed-`-v` branches so coverage stays at 100% on `src/mcp/cli/cli.py`. Also drop the now-obsolete `# pragma: no cover` from `_parse_env_var` (it's exercised through `_resolve_env`).
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Summary
Closes #339.
mcp installalready accepts--env-var/-vand--env-file/-f, butmcp devdid not — so there was no way to pass environment variables to a server when iterating with the inspector. This PR adds the same two flags tomcp devand routes the resolved values into the inspector subprocess environment.Changes
--env-var/-vand--env-file/-foptions tomcp dev(mirrorsmcp install)._resolve_env(env_file, env_vars)helper; inline-vvalues override.envvalues.mcp installto use the helper (no behavior change, removes duplication).README.v2.md._resolve_envcovering: no inputs, inline vars, values containing=, dotenv loading, and inline-overrides-dotenv.Validation
uv run --frozen ruff format/ruff check— cleanuv run --frozen pyright src/mcp/cli/cli.py tests/cli/test_utils.py— 0 errorsuv run --frozen pytest tests/cli/test_utils.py— 14 passed