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docs: say "safe integer" for progressToken, matching what the code enforces

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The copy said `progressToken` may be "an integer" while the implementation
validates with `ProgressTokenSchema` — zod's `.int()`, which rejects anything
past `Number.MAX_SAFE_INTEGER`. This repo's own tests assert that
`MAX_SAFE_INTEGER + 1` is dropped, so the documentation was promising a value
the client discards.

Corrected in all three places, so the code comment, the docs callout and the UI
hint agree: `dropInvalidReservedMeta`'s doc block (which review did not flag),
the `metadata` reserved-keys callout, and the Request Metadata hint.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0177mPHAdECD18nLLCTwR5rh
Signed-off-by: cliffhall <cliff@futurescale.com>
This commit is contained in:
cliffhall 2026-08-23 19:31:50 -04:00
commit 129a435fd4
3 changed files with 5 additions and 3 deletions
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3
clients/web/src/components/groups/ServerSettingsForm/ServerSettingsForm.tsx
View file

@ -734,7 +734,8 @@ export function ServerSettingsForm({
objects, arrays, numbers, booleans, <Code>null</Code> — not just
strings. Leave it as <Code>{"{}"}</Code> to send none. The keys
the protocol reserves keep their own shape:{" "}
<Code>progressToken</Code> must be a string or an integer, and{" "}
<Code>progressToken</Code> must be a string or a safe integer (one
JavaScript can represent exactly), and{" "}
<Code>io.modelcontextprotocol/related-task</Code> an object with a
string <Code>taskId</Code>. A reserved key that does not match is
dropped from the request rather than sent.

3
core/mcp/inspectorClient.ts
View file

@ -401,7 +401,8 @@ function isProgressToken(value: unknown): value is ProgressToken {
* Drop the reserved `_meta` members whose value the protocol will not accept.
*
* Most of `_meta` is arbitrary JSON (#1910), but a few keys are **reserved**
* and carry their own schema — `progressToken` (`string | integer`) and
* and carry their own schema — `progressToken` (a string or a safe integer;
* zod's `.int()` rejects anything past `Number.MAX_SAFE_INTEGER`) and
* `io.modelcontextprotocol/related-task` (`{ taskId: string }`) in the pinned
* SDK. Before the widening every value was a string, so only `progressToken`
* could even be wrong; now any of them can, and one bad reserved member makes a

2
docs/mcp-server-configuration.md
View file

@ -187,7 +187,7 @@ These have no analog in the broader `mcp.json` ecosystem. Each is **omitted on w
}
```
> **A few keys are reserved and keep their own shape.** "Any JSON" holds for keys you invent, not for the ones the protocol defines. In the current SDK those are `progressToken` (a string or an integer) and `io.modelcontextprotocol/related-task` (`{ "taskId": "<string>" }`). A reserved key whose value does not match is **dropped from the outgoing request**, with a warning naming the key — because a conforming server rejects the _entire_ request over one bad reserved member, rather than ignoring that key. Everything else in the payload is sent unchanged.
> **A few keys are reserved and keep their own shape.** "Any JSON" holds for keys you invent, not for the ones the protocol defines. In the current SDK those are `progressToken` (a string or a **safe** integer — one JavaScript represents exactly, so nothing past `Number.MAX_SAFE_INTEGER`) and `io.modelcontextprotocol/related-task` (`{ "taskId": "<string>" }`). A reserved key whose value does not match is **dropped from the outgoing request**, with a warning naming the key — because a conforming server rejects the _entire_ request over one bad reserved member, rather than ignoring that key. Everything else in the payload is sent unchanged.
> **Not yet applied by the CLI.** The web client and the TUI both send this payload on every request. The CLI does not — it never passes the persisted value to its client, so a `metadata` entry is currently inert for `--cli` runs ([#2093](https://github.com/modelcontextprotocol/inspector/issues/2093)). Use the per-invocation `--metadata` flag there in the meantime.