Replaces FastMCP.as_proxy() helper calls with create_proxy(), rewrites the
mount() as_proxy=/prefix= kwarg tests to plain mount() (the params are gone),
and deletes deprecation-only tests for as_proxy() and remove_tool().
* OTEL: Fix attribute compliance and improve telemetry helpers
Attribute compliance:
- Remove rpc.system/service/method (MCP is not traditional RPC)
- Add gen_ai.tool.name on tools/call spans
- Add gen_ai.prompt.name on prompts/get spans
- Fix session_id check (truthy -> is not None)
Telemetry helper improvements:
- Add is_recording() guards to skip work on non-recording spans
- Add error.type attribute with __qualname__ on error spans
- Use isinstance check for ToolError to set "tool_error" error type
- Include exception message in span status description
- Add tool_name/prompt_name params to server_span and client_span
Client call_tool enrichment:
- Reflect tool-level errors (result.isError) on client span status
so callers see ERROR even though the MCP protocol call succeeded
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: remove resource URI from span names to avoid high-cardinality
Per MCP semantic conventions, resource URIs SHOULD NOT be included in
span names by default since they can be unbounded (especially with
templates like users://{id}/profile). The URI remains available via
the mcp.resource.uri attribute.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: add missing gen_ai/mcp attributes to proxy and delegate spans
- Proxy tool spans: add gen_ai.tool.name
- Proxy prompt spans: add gen_ai.prompt.name
- All delegate spans: add mcp.method.name
- Docs: remove rpc.* references, update span names and attributes table
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Hoist ToolError imports to module level, add rpc.* migration note
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: resolve OpenAPI 3.x server variables in _create_default_client
When an OpenAPI spec defines server variables (e.g. `https://{region}.api.example.com/v1`),
the default values are now substituted before constructing the httpx client base URL.
Previously, the URL was used as-is, causing all requests to fail for specs that use
server variable templating.
Fixes#1681
* fix: use str.replace instead of format_map for server variable substitution
format_map applies Python string formatting rules, so variable names
like {api.version} would be treated as attribute access and raise errors.
Literal token replacement handles all valid OpenAPI variable names safely.
* fix: task.wait() now returns on input_required instead of hanging
Previously, wait() used a terminal-state allowlist (completed, failed,
cancelled), so tasks entering input_required would hang until timeout.
Replaced with inverse logic: return whenever the task exits the 'working'
state. This handles input_required and any future blocking states without
needing to update the allowlist.
Fixes#3779
* fix: include submitted in in_progress_states to avoid premature return
* fix: revert submitted, update state docstring to match MCP spec
* fix: add _wait_terminal() so result() waits for completed/failed/cancelled
wait() correctly returns on input_required for human-in-the-loop use cases,
but result() needs to wait until the task fully resolves. Add a private
_wait_terminal() helper that loops through non-terminal states and use it
in all result() implementations.
* fix: elicitation scalar return, resource auto-serialization, Client.new() state, prompt errors
- Auto-wrap scalar elicitation responses for ScalarElicitationType schemas
so handlers can return T directly for ctx.elicit("msg", str/int/float)
- Auto-serialize dict/int/float/bool/None resource returns to JSON text
instead of crashing with TypeError
- Reset _task_registry and _submitted_task_ids in Client.new() so cloned
clients have independent task tracking state
- Include original error message in prompt render errors (matching tool
error behavior)
Fixes#3856
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix misleading comment and add list/tuple auto-serialization for resources
The comment said "list/tuple of primitives" but the isinstance check
didn't include list or tuple. Now it does, and the comment matches.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix TaskNotificationHandler binding in Client.new() and meta forwarding for JSON resources
Two review-identified bugs:
1. Client.new() shallow-copies _session_kwargs, so the cloned client's
TaskNotificationHandler still dispatches to the original client.
Fix: create a fresh _session_kwargs dict with a new handler bound
to the new client.
2. convert_result() for dict/int/float/bool/None fell through to
ResourceResult(raw_value) which lost component meta (CSP, permissions).
The str/bytes path correctly wrapped in ResourceContent with meta.
Fix: explicitly serialize JSON-native types and wrap with meta,
matching the str/bytes path. Other types still fall through for
error handling.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Preserve custom message handlers in Client.new()
Only replace the message handler with a new TaskNotificationHandler
if the current handler IS a TaskNotificationHandler. If the user
provided a custom message_handler, preserve it in the clone.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix client.new and add regression tests
* Honor declared MIME type for auto-serialized JSON resources
* Fix static analysis: remove unused StdioTransport import, fix ty:ignore comment
* Exclude list[ResourceContent] from JSON auto-serialization path
A bare list[ResourceContent] would match the isinstance(list) check
and get JSON-serialized instead of passing through to ResourceResult
normalization. Check for ResourceContent items first.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
When a tool returns `list[dict]`, the client deserializes each dict as a
`Root()` dataclass with no fields instead of preserving the original dict
data.
The root cause is in `_get_from_type_handler`: its `"object"` branch
always fell through to `_create_dataclass` for schemas without
`properties`, creating an empty dataclass named `Root`. The top-level
`json_schema_to_type` already handled this case correctly (returning
`dict[str, Any]`), but that logic was not shared with `_schema_to_type`
which is used when converting nested schemas (e.g., array items).
Extract `_object_schema_to_type` to unify the four object-schema cases
(dict, typed dict, BaseModel with extra, dataclass) so both top-level
and nested paths produce the correct type.
Fixes#3867
Co-authored-by: Ke Wang <ke@pika.art>
* Cap consecutive final_response validation retries to 3
Previously, when the LLM repeatedly called final_response with data that
failed validation, the retry loop would continue up to 100 times (the
shared max_iterations limit), wasting tokens on a model that cannot
satisfy the schema.
Add _MAX_VALIDATION_RETRIES (default 3) that caps consecutive validation
failures. The counter resets when the LLM calls other tools (not
final_response), so the cap only applies to consecutive failures.
Fixes#3848
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Add tests for consecutive validation retry cap
Tests cover:
- Validation failures within cap followed by success
- Consecutive validation failures exceeding cap (raises RuntimeError)
- Counter reset when LLM calls other tools between validation failures
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Slim down validation retry cap tests
Reduce boilerplate with helper functions.
Simplify counter-reset test from 5 calls to 4.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix static analysis: move imports to module level and format
Move CreateMessageResultWithTools and ToolUseContent imports to the
top of the test file so ty can resolve the names used in return-type
annotations of the helper functions. Also fix ruff import sorting
and formatting issues.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Align validation retry semantics with text-response retries
Change `>=` to `>` so _MAX_VALIDATION_RETRIES means "number of
retries after the initial attempt" (total = N+1), matching the
convention used by _MAX_TEXT_RESPONSE_RETRIES in the text-response
retry path.
Before: _MAX=3 meant 3 total attempts (>= comparison)
After: _MAX=3 means 1 initial + 3 retries = 4 total (> comparison)
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix GoogleGenaiSamplingHandler thought part leaking and unhelpful errors
- Filter thought parts (part.thought=True) from response content instead
of leaking them as TextContent in _response_to_result_with_tools
- Include finish_reason in error messages when no content is found, so
safety-filtered responses (SAFETY, RECITATION, etc.) are distinguishable
- Add specific error message for thinking-only responses in
_response_to_create_message_result
Fixes#3846
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Add tests for thought part filtering and error message improvements
Tests cover:
- Thought parts filtered from tool-path responses
- Thought-only responses produce descriptive errors
- Safety-filtered responses include finish_reason in error
- Normal responses (text + function calls) unaffected
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix ruff format and ty check issues
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix ty check errors in tests
Remove unused ty: ignore comments from lines where isinstance() narrows
the type, and add correct ty: ignore[invalid-argument-type] and
ty: ignore[not-subscriptable] comments on lines in newly added test
functions where ty cannot infer the union type is a list. Also apply
ruff format fix in test_task_return_types.py.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix: use all() not any() for thinking-only detection
Addresses review feedback: any() would misclassify mixed responses
(thought + function_call) as thinking-only, hiding the real error.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Raise on unhandled content types in sampling handler dispatch chains
The Anthropic and OpenAI sampling handlers have isinstance chains that
dispatch on MCP content types but silently drop unhandled variants like
EmbeddedResource and ResourceLink. This adds explicit else-raise guards
to match the Gemini handler's behavior and the single-content dispatch
paths that already raise.
Raising is the right choice over warn-and-skip: a partial conversion
produces a plausible-but-wrong LLM response (the model confidently
answers based on incomplete input), which is worse than a clear error
that tells the user exactly what isn't supported.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Add tests for unsupported content type raises in sampling handlers
Tests the new ValueError raises for unsupported content types
(e.g. EmbeddedResource) in the Anthropic and OpenAI message
conversion loops. Uses model_construct to bypass Pydantic's
union validation since the raise is a defensive guard for
future SDK content types.
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Retry when LLM returns text instead of calling final_response tool
Instead of raising RuntimeError immediately when the LLM returns a text
response instead of calling the `final_response` tool for structured
output, retry up to 3 times with an explicit nudge message asking the
model to use the tool. This mirrors the existing retry behavior for
validation errors but with a separate, smaller cap.
Fixes#3847
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Add tests for text response retry logic
Tests cover:
- Text response followed by successful final_response (retry works)
- Text response exceeding max retries (raises RuntimeError)
- Nudge message appended to history on retry
- No retry when result_type is None (text is valid)
Addresses review feedback from PR review tool (v1 flagged missing tests as high severity).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Slim down text response retry tests
Remove test_nudge_message_in_history (implementation detail).
Reduce boilerplate in remaining 3 tests.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix ruff format
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: strip title fields from tool schemas for Gemini compatibility
Gemini 2.5 Flash produces MALFORMED_FUNCTION_CALL when a function
declaration's parameters_json_schema contains 'title' fields (which
Pydantic adds by default). Strip them in _convert_tool_to_google_genai
before passing to the API.
Fixes#3860
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* Fix ty errors and lowest-deps test failure
- Add assertions for non-None before subscripting FunctionDeclaration
fields (ty check)
- Test compress_schema directly instead of constructing FunctionDeclaration
which may not support parameters_json_schema in google-genai==1.18.0
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: recover StdioTransport after subprocess exits
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix: improve Windows reliability for stdio crash recovery
🤖 Generated with Claude Code
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* feat: support ImageContent and AudioContent in sampling handlers
Co-authored-by: Claude <noreply@anthropic.com>
* Validate image MIME types, fix silent drop in assistant list messages
* Reject image/audio in assistant messages with tool_calls
* Reject ImageContent in assistant messages for Anthropic
---------
Co-authored-by: Claude <noreply@anthropic.com>
* fix: stop passing follow_redirects to httpx_client_factory
Remove the `follow_redirects=True` kwarg that was being forced onto
custom httpx_client_factory calls with a type: ignore suppression.
The McpHttpClientFactory protocol does not include follow_redirects,
so this was a protocol violation. httpx already strips Authorization
headers on cross-origin redirects via its _redirect_headers mechanism.
🤖 Co-authored-by: Claude <noreply@anthropic.com>
* fix: restore follow_redirects=True for custom httpx client factories
httpx already strips Authorization headers on cross-origin redirects,
so follow_redirects is safe to keep. Removing it broke redirect
handling for users providing custom factories.
* fix: remove vacuous test that never invoked connect_session
The test asserted on received_kwargs but never called connect_session,
so the factory was never invoked and the assertion was a no-op.
* fix: use AsyncClient with transport= instead of monkey-patching _transport
- Use 10 PBKDF2 iterations in test_mode (vs 1M in production) for
JWT key derivation — cuts auth test setup from ~2.5s to <0.1s
- Add timeout(15) to subprocess-spawning tests (TestKeepAlive,
test_mcp_config) that exceed 5s under parallel CI load
- Remove pytestmark filterwarnings overrides in tests/deprecated/
that were leaking DeprecationWarning to test output
- Fix deprecated add_tool_transformation() usage in test_authorization
- Document new settings in settings.mdx
* perf: expose minimum_check_interval, reduce task pickup latency
The Docket Worker polls for new tasks every minimum_check_interval
(previously hardcoded to 250ms in pydocket). Expose this setting so
users can tune it, default to 50ms, and override to 10ms in tests.
This cuts average task pickup latency from ~125ms to ~5ms per task.
* perf: reduce task test overhead and eliminate cross-test contamination
- Expose minimum_check_interval setting (default 50ms, 10ms in tests)
to reduce Docket Worker task pickup latency
- Isolate fakeredis per test via unique memory:// URLs to prevent
stale _async_blocking tasks from contaminating subsequent tests
- Make client disconnect timeout configurable (default 5s, 1s in tests)
- Add --durations=50 to CI for passive performance regression detection
- Remove 15s timeout band-aids from task test conftest files
- Add explicit @pytest.mark.timeout(10) to cancellation tests
- Fix deprecated FastMCP.as_proxy() usage in test_task_proxy.py
Fix context manager ordering in FastMCPTransport so the task group
(server run + subscriptions) is cancelled before the lifespan
(Docket Worker) tears down. Also break subscription loop on terminal
task states.
Closes#3498
* feat: add `verify` parameter for SSL certificate configuration
* Propagate verify to OAuth preflight clients
* Propagate verify to pre-constructed OAuth instances
* Fix verify override not propagating to existing OAuth factory
* Warn when both httpx_client_factory and verify are provided
* Preserve user-provided OAuth factory when transport has verify
* Skip OAuth re-sync when transport has custom httpx_client_factory
* Propagate x-fastmcp-wrap-result flag in tool result _meta
🤖 Generated with Claude Code
Co-authored-by: Claude <noreply@anthropic.com>
* Skip listTools round-trip when _meta has x-fastmcp-wrap-result
🤖 Generated with Claude Code
Co-authored-by: Claude <noreply@anthropic.com>
* Use namespaced meta key: {"fastmcp": {"wrap_result": true}}
🤖 Generated with Claude Code
Co-authored-by: Claude <noreply@anthropic.com>
* Clean up _parse_call_tool_result: hoist cast import, document local CallToolResult import, extract fastmcp_meta
🤖 Generated with Claude Code
Co-authored-by: Claude <noreply@anthropic.com>
* Merge _meta in tasks result handler instead of overwriting
🤖 Generated with Claude Code
* Preserve type validation in meta-based unwrap path
🤖 Generated with Claude Code
* Fix type validation for wrapped task results, guard non-dict meta
🤖 Generated with Claude Code
---------
Co-authored-by: Claude <noreply@anthropic.com>
* fix: shield lifespan teardown from cancellation
Co-authored-by: Claude <noreply@anthropic.com>
* fix: stabilize flaky task and timeout tests under parallel execution
Co-authored-by: Claude <noreply@anthropic.com>
---------
Co-authored-by: Claude <noreply@anthropic.com>
* Add Google GenAI sampling handler
Co-authored-by: Bill Easton <strawgate@users.noreply.github.com>
* chore: Update SDK documentation
* Filter non-Gemini model hints in _get_model
Match the Anthropic/OpenAI handler pattern of only selecting
provider-compatible models from hints.
---------
Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Bill Easton <strawgate@users.noreply.github.com>
Co-authored-by: marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com>
Co-authored-by: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
The client timeout of 0.1s was too tight — the SSE handshake alone
consumed it under CI load before the tool call ever started. Raised
to 0.5s which still validates the precedence logic.
* Update repository references from jlowin/fastmcp to prefecthq/fastmcp
* Retrigger CI after repo transfer
* chore: Update SDK documentation
* Only run deep triage on bug issues for jlowin
---------
Co-authored-by: marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com>
