inspector/pr-screenshots

Advertised-extensions toggle (#1739) — proof screenshots

End-to-end verification of the advertised-extensions debugging knob against a real legacy HTTP test server (test-servers/configs/advertised-extensions-http.json on port 3220), driven in a real browser through the web client's remote-proxy transport. The server registers echo (always) and get_weather gated on the io.modelcontextprotocol/tasks extension (extensionGatedTools): the tool is enabled on notifications/initialized only when the connected client declared that extension.

Server Settings → Advertised Extensions (the new section). With no override, Tasks (io.modelcontextprotocol/tasks) is checked — the registry default — so the Inspector advertises it in its client capabilities.

Connected with Tasks advertised. The server sees the declared extension on initialized and enables the gated tool, so tools/list returns both echo and get_weather.

Unchecking Tasks writes the per-server advertisedExtensions override. The change takes effect on the next connect (as the section note says).

After reconnecting, the client advertises no extensions, so the server never enables the gated tool — tools/list now returns only echo. The server's tool registration demonstrably changed based on what the client advertised, exactly the acceptance criterion for #1739.

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x-mcp-header Tools tooling (#1632) — proof screenshots

End-to-end verification of the SEP-2243 x-mcp-header Tools tooling against a real modern (2026-07-28) HTTP test server (test-servers/configs/xmcpheader-modern-http.json on port 3120), driven in a real browser through the web client's remote-proxy transport.

Connected with Protocol Era = Modern. invalid_header_tool is dropped from tools/list by the SDK (its x-mcp-header annotation is invalid), so the Inspector re-lists the raw list and surfaces it struck-through under an "Excluded (SEP-2243)" divider — showing why a tool vanished rather than silently omitting it.

Hovering the excluded tool shows the exact scan reason: the header name "Bad Header" contains a space, so it is not a valid RFC 9110 token.

get_weather's detail panel shows the "Mirrored request headers (SEP-2243)" section: its city argument mirrors to Mcp-Param-City, with the note that the SDK omits Mcp-Param-* on the browser transport.

Calling a tool the server no longer recognizes rejects with -32602 (SDK v2) instead of an isError result, and renders as an "Unknown Tool" error panel with a targeted hint (reproduced by swapping the sessionless server to one without echo while the cached list still showed it).

-32602 is the generic Invalid params code, so a known tool rejected for bad arguments throws the same code as an unknown tool. The panel disambiguates from the message: a -32602 that does not name an unknown tool renders under "Invalid Parameters" (with a schema hint) rather than "Unknown Tool". Triggered live via the trigger_invalid_params tool, which returns a real -32602 JSON-RPC error whose message is not about a missing tool.

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Tasks extension era fork (#1631) — proof screenshots

End-to-end verification of the Tasks era fork against two real test servers (test-servers/configs/tasks-modern-http.json on port 3222 and tasks-legacy-http.json on 3223), driven in a real browser through the web client's remote-proxy transport.

Modern era (2026-07-28, io.modelcontextprotocol/tasks extension)

Connected with Protocol Era = Modern (MCP 2026-07-28). The Tasks tab appears in the monitoring sidebar because the io.modelcontextprotocol/tasks extension was negotiated (it is empty until a task runs).

Connected with Protocol Era = Modern (MCP 2026-07-28). The Tasks tab is gated on the negotiated io.modelcontextprotocol/tasks extension (not capabilities.tasks). Running modern_task with Run as task on issues a tools/call that returns a CreateTaskResult (resultType: "task"), then polls tasks/get (no tasks/list); the completed task inlines its result (no blocking tasks/result) — shown both in the Results panel and the Tasks card.

modern_input_task moves to input_required: the tasks/get response's inputRequests map (visible in the task's Full Task Object) carries an embedded elicitation/create, surfaced through the same pending-request modal the MRTR path uses — note the accurate wording "your answer is submitted via a tasks/update request (SEP-2663), not a retry". Answering it sends tasks/update with the inputResponses, and the next poll completes the task:

Legacy era (2025-11-25, contrast — unchanged)

Connected with Protocol Era = Legacy. The Tasks tab is gated on capabilities.tasks; simple_task is taskSupport: "required" so Run as task is forced on. The legacy flow uses tasks/list to populate the list, tasks/get to poll, and the blocking tasks/result to fetch the payload ({ "message": "Task completed: no message", "taskId": … }). Note the legacy-only Logs tab (this server advertises logging), absent from the modern monitor set.

Notes

• SDK v2 removed all tasks support and era-gates the tasks/* spec methods out of the 2026-07-28 era on both the client (outbound) and server (inbound), and its codec rejects a resultType: "task" result outright. So the Inspector drives the extension itself: the task-creation frame is rewritten at the transport into a CallToolResult carrying the handle (the true resultType: "task" frame is still logged to the Protocol/Network tabs), and tasks/get / tasks/update / tasks/cancel ride a raw-wire request channel that carries the full modern envelope and is consumed by the transport before the SDK Client sees it. The test server serves tasks/* from an Express interceptor ahead of the SDK handler (the SDK's modern leg would answer them -32601).
• On modern, task creation is server-directed (SEP-2663): the client declares the extension once and any tool may return a task, so the Tools screen offers Run as task for every tool on a modern connection (rather than gating on the legacy per-tool taskSupport).