René's URL Explorer Experiment

Title: Conformance burn-down: server-side InputRequiredResult, Mcp-Method/Name validation, x-mcp-header filter (14 scenarios → green) by maxisbey · Pull Request #2974 · modelcontextprotocol/python-sdk · GitHub

Open Graph Title: Conformance burn-down: server-side InputRequiredResult, Mcp-Method/Name validation, x-mcp-header filter (14 scenarios → green) by maxisbey · Pull Request #2974 · modelcontextprotocol/python-sdk

X Title: Conformance burn-down: server-side InputRequiredResult, Mcp-Method/Name validation, x-mcp-header filter (14 scenarios → green) by maxisbey · Pull Request #2974 · modelcontextprotocol/python-sdk

Description: Bumps the conformance pin to 0.2.0-alpha.7 and clears 14 scenarios from the expected-failures baseline, leaving only the 4 that depend on unlanded design (client Mcp-Param-* emission, modern stateless SSE for progress, MCPServer prompt-pipeline InputRequiredResult, and the SEP-990 enterprise-auth waiver). Motivation and Context #2967 widened the lowlevel server return types for InputRequiredResult and #2968 gave Client.call_tool the allow_input_required / input_responses / request_state surface, but neither was reachable through the conformance harness: the everything-server had no MRTR fixture tools, the client driver had no SEP-2322 handler, and MCPServer's func_metadata.convert_result() still mangled an InputRequiredResult into TextContent. Separately, the SEP-2243 boundary checks (Mcp-Method/Mcp-Name cross-check, x-mcp-header validity) were unimplemented on both sides. This closes those gaps. How Has This Been Tested? All five conformance legs run green with --expected-failures at @modelcontextprotocol/conformance@0.2.0-alpha.7: Leg Result server --suite active 42 pass / 0 fail server --suite draft 69 pass / 1 expected fail server --suite all --spec-version 2026-07-28 97 pass / 2 expected fail client --suite all 402 pass / 7 expected fail (2 scenarios) client --suite all --spec-version 2026-07-28 352 pass / 5 expected fail (1 scenario) ./scripts/test: 2776 passed, 100% coverage, strict-no-cover clean. pyright: 0 errors. Breaking Changes None for v1-lineage callers. At 2026-07-28, ClientSession.list_tools() now drops tools whose x-mcp-header annotations are invalid (the spec MUST is on the client); handshake-era sessions are unaffected. The modern HTTP server entry now rejects requests where Mcp-Method/Mcp-Name headers contradict the body — handshake-era requests don't pass through that classifier rung. Types of changes Bug fix (non-breaking change which fixes an issue) New feature (non-breaking change which adds functionality) Breaking change (fix or feature that would cause existing functionality to change) Documentation update Checklist I have read the MCP Documentation My code follows the repository's style guidelines New and existing tests pass locally I have added appropriate error handling I have added or updated documentation as needed Additional context SDK changes func_metadata.convert_result() passes InputRequiredResult through; MCPServer._handle_call_tool / call_tool return type widened to CallToolResult | InputRequiredResult. Context gains .input_responses / .request_state / .client_capabilities read-only props so a tool body can read what the client supplied. shared/inbound.py: classify_inbound_request rung 2 cross-checks Mcp-Method == body.method and Mcp-Name == params.{name|uri} (new NAME_BEARING_METHODS map + decode_header_value). New find_invalid_x_mcp_header() validates the annotation per RFC 9110 token rules + uniqueness + primitive-type. _streamable_http_modern.py filters tools/list results for invalid x-mcp-header at the modern HTTP boundary (so the version gate is structural, not a conditional in handler code). ClientSession.list_tools applies the same filter when the negotiated version is modern. _make_modern_stamp now derives Mcp-Name from NAME_BEARING_METHODS (covers prompts/get and resources/read, not just tools/call); send_discover stamps Mcp-Method so the auto-mode probe doesn't fail the cross-check it just introduced. Fixtures everything-server: 8 test_input_required_result_* tools (elicitation/sampling/list_roots/request_state/multiple_inputs/multi_round/tampered_state/capabilities) + json_schema_2020_12_tool carrying the 2020-12 keywords the scenario checks. The tampered_state tool uses a fixture-local hmac to sign/verify requestState; an SDK-level helper is follow-up. .github/actions/conformance/client.py: handlers for sep-2322-client-request-state (drives the four mock tools via allow_input_required=True) and http-invalid-tool-headers (lists then calls every surfaced tool). Pin CONFORMANCE_PKG moves from the pkg.pr.new@65fcd39 URL to the published @modelcontextprotocol/conformance@0.2.0-alpha.7; the URL fetch-and-verify steps are dropped now that npm's own integrity check applies. Baselined: alpha.7 introduces no new failures over the previous pin. Stacked on #2968. AI Disclaimer

Open Graph Description: Bumps the conformance pin to 0.2.0-alpha.7 and clears 14 scenarios from the expected-failures baseline, leaving only the 4 that depend on unlanded design (client Mcp-Param-* emission, modern statel...

X Description: Bumps the conformance pin to 0.2.0-alpha.7 and clears 14 scenarios from the expected-failures baseline, leaving only the 4 that depend on unlanded design (client Mcp-Param-* emission, modern statel...

Opengraph URL: https://github.com/modelcontextprotocol/python-sdk/pull/2974

X: @github

direct link

Domain: github.com

Links:

Viewport: width=device-width