fix: resolve Pyright "Module is not callable" on @tool, @resource, @prompt decorators#3540
fix: resolve Pyright "Module is not callable" on @tool, @resource, @prompt decorators#3540
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| f"Importing {name} from fastmcp.tools.base is deprecated. " | ||
| f"Import from fastmcp.tools.function_tool instead.", |
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Renaming fastmcp.tools.tool to fastmcp.tools.base (and similarly for prompts/resources) removes the old module path entirely, so existing code now fails at import time with ModuleNotFoundError instead of receiving the deprecation warning that existed before this commit. This is a real compatibility regression because the old paths are still used in repo docs/examples (for example docs/servers/tools.mdx:672 and examples/tool_result_echo.py:13 import from fastmcp.tools.tool import ToolResult), so users following current guidance will break on upgrade unless a shim module or alias is kept.
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| # Preserve the old import path (fastmcp.tools.tool) for backward compatibility. | ||
| # The module was renamed to base.py to avoid shadowing the `tool` decorator function, | ||
| # which caused Pyright to report "Module is not callable" errors. | ||
| sys.modules[f"{__name__}.tool"] = sys.modules[f"{__name__}.base"] |
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The new sys.modules alias preserves from fastmcp.tools.tool import ..., but it does not preserve the common import fastmcp.tools.tool module-import behavior: after import, fastmcp.tools.tool on the package still resolves to the decorator function, so fastmcp.tools.tool.ToolResult now raises AttributeError. This is a backward-compatibility regression for code that imported the old submodule path as a module (the same pattern exists for prompts/resources), even though this block is intended to preserve the legacy path.
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| # Preserve the old import path (fastmcp.tools.tool) for backward compatibility. | ||
| # The module was renamed to base.py to avoid shadowing the `tool` decorator function, | ||
| # which caused Pyright to report "Module is not callable" errors. | ||
| sys.modules[f"{__name__}.tool"] = sys.modules[f"{__name__}.base"] |
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Aliasing fastmcp.tools.tool to fastmcp.tools.base only through sys.modules keeps from fastmcp.tools.tool import ... working, but it drops module discovery metadata: in this commit importlib.util.find_spec("fastmcp.tools.tool") (and the analogous prompt/resource paths) now returns None, while it resolved before the rename. This breaks callers that gate imports via find_spec or execute modules via python -m, so the compatibility path needs a real shim module (or equivalent spec-preserving approach), not just a runtime alias.
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Co-authored-by: Claude Opus 4.6 <[email protected]> Co-authored-by: Jeremiah Lowin <[email protected]> Co-authored-by: Marvin Context Protocol <41898282+Marvin Context [email protected]> Co-authored-by: voidborne-d <[email protected]> Co-authored-by: marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com> Co-authored-by: Claude <[email protected]> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: d 🔹 <[email protected]> Co-authored-by: Jeremiah Lowin <[email protected]> Co-authored-by: nightcityblade <[email protected]> Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]> Co-authored-by: Claude Sonnet 4.6 <[email protected]> Co-authored-by: Bill Easton <[email protected]> Co-authored-by: Sumanshu Nankana <[email protected]> Co-authored-by: Eric Robinson <[email protected]> Co-authored-by: Martim Santos <[email protected]> Co-authored-by: d 🔹 <[email protected]> Co-authored-by: Matthieu B <[email protected]> Co-authored-by: Sascha Buehrle <[email protected]> Co-authored-by: Hakancan <[email protected]> Co-authored-by: nightcityblade <[email protected]> Co-authored-by: Matt Hallowell <[email protected]> Co-authored-by: nate nowack <[email protected]> Co-authored-by: Bill Easton <[email protected]> Co-authored-by: Marcus Shu <[email protected]> Co-authored-by: Rushabh Doshi <[email protected]> Co-authored-by: AIKAWA Shigechika <[email protected]> Co-authored-by: Jeremy Simon <[email protected]> Co-authored-by: Miguel Miranda Dias <[email protected]> Co-authored-by: Anthony James Padavano <[email protected]> Co-authored-by: Mostafa Kamal <[email protected]> Fix auto-close MRE script posting comment without closing (#3386) Fix WorkOS token scope verification bypass 🤖 Generated with Codex (#3407) Fix initialize McpError fallthrough 🤖 Generated with Codex (#3413) Fix transform arg collisions with passthrough params (#3431) Fix get_* returning None when latest version is disabled (#3439) Fix get_* returning None when latest version is disabled (#3421) Fix server lifespan overlap teardown (#3415) Fix $ref output schema object detection regression (#3420) resolved annotations (#3429) Fix async partial callables rejected by iscoroutinefunction (#3438) Fix async partial callables rejected by iscoroutinefunction (#3423) fix: add version to components (#3458) fix: use intent-based flag for OIDC scope patch in load_access_token (#3465) Fixes #3461 fix: normalize Google scope shorthands and surface valid_scopes (#3477) fix: resolve ty 0.0.23 type-checking errors and bump pin (#3481) fix: shield lifespan teardown from cancellation (#3480) fix: forward custom_route endpoints from mounted servers (#3462) fix updates _get_additional_http_routes() to traverse providers, Fixes #3457 fix: remove hardcoded version from CLI help text (#3456) fix: monty 0.0.8 compatibility, drop external_functions from constructor (#3468) fix: task test teardown hanging 5s per test (#3499) Closes #3498 fix: validate workspace path is a directory before cursor install (#3440) Fixes #3426 fix: handle re.error from malformed URI templates in build_regex (#3501) fix: reject empty/OIDC-only required_scopes in AzureProvider (#3503) fix: restrict $ref resolution to local refs only (SSRF/LFI) (#3502) fix warnings and timeouts (#3504) close upgrade check issue when build passes (#3505) Closes #3484 fix: URL-encode path params to prevent SSRF/path traversal (GHSA-vv7q-7jx5-f767) (#3507) fix: prevent path traversal in skill download (#3493) fix: prefer IdP-granted scopes over client-requested scopes in OAuthProxy (#3492) fix: remove unrelated transform and http.py changes from PR scope fix: remove forced follow_redirects from httpx_client_factory calls (#3496) fix: stop passing follow_redirects to httpx_client_factory fix: restore follow_redirects=True for custom httpx client factories Closes #3509 fix: CSRF double-submit cookie check in consent flow (#3519) fix: validate server names in install commands (#3522) fix: use raw strings for regex in pytest.raises match (#3523) fix: reject refresh tokens used as Bearer access tokens (#3524) fix: route ResourcesAsTools/PromptsAsTools through server middleware (#3495) fix: resolve Pyright "Module is not callable" on @tool, @resource, @prompt decorators (#3540) fix: filter warnings by message in KEY_PREFIX test (#3549) fix: suppress output schema for ToolResult subclass annotations (#3548) fix: increase sleep duration in proxy cache tests (#3567) fix: store absolute token expiry to prevent stale expires_in on reload (#3572) fix: preserve tool properties named 'title' during schema compression (#3582) Fix loopback redirect URI port matching per RFC 8252 §7.3 (#3589) Fix app tool routing: visibility check and middleware propagation (#3591) Fix query parameter serialization to respect OpenAPI explode/style settings (#3595) Fix dev apps form: union types, textarea support, JSON parsing (#3597) fix(google): replace deprecated /oauth2/v1/tokeninfo with /oauth2/v3/userinfo (#3603) fix: resolve EntraOBOToken dependency injection through MultiAuth (#3609) fix(docs): correct misleading stateless_http header (#3622) fix: filesystem provider import machinery (#3626) Closes #3625 (issues 2, 3, 6) fix: recover StdioTransport after subprocess exits (#3630) fix(server): preserve mounted tool task metadata (#3632) fix: scope deprecation warning filter to FastMCPDeprecationWarning (#3649) fix imports, add PrefabAppConfig (#3650) fix: resolve CurrentFastMCP/ctx.fastmcp to child server in mounted background tasks (#3651) Fix blocking docs issues: chart imports, Select API, Rx consistency (#3652) closed by default (#3657) Fix prompt caching middleware missing wrap/unwrap round-trip (#3666) fix: serialize object query params per OpenAPI style/explode rules (#3662) Fixes #2857 fix: HTTP request headers not accessible in background task workers (#3631) fix: restore HTTP headers in worker execution path for background tasks (#3681) fix: strip discriminator after dereferencing schemas (#3682) fix: remove stale ty:ignore directives for ty 0.0.26 (#3684) Fix docs gaps in app provider pages (#3690) fix: dev apps log panel UX improvements (#3698) fix dev server empty string args (#3700)
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The
tools/,prompts/, andresources/packages each had a submodule with the same name as the decorator function they export (tool.py,prompt.py,resource.py). Python's runtime resolvesfrom fastmcp.tools import toolcorrectly —__init__.pyshadows the submodule — but Pyright sees the ambiguity and resolves it as the module, producing a "Module is not callable" error when the decorator is applied.The fix renames these files to
base.py, eliminating the name collision.sys.modulesshims preserve the old submodule import paths (from fastmcp.tools.tool import Tool, etc.) at runtime so existing code doesn't break, even though those paths were never part of the documented API.Closes #3530