Adrian Cole

recheck

@samsp-msft, thanks for your thoughtful feedback! I’ve updated the "Basic" section to keep it neutral and avoid implying MCP defines OpenTelemetry (OTel) specifics: ``` - Params **MAY** include a `_meta`...

I took time to update the description with feedback in the comments and also relating to discussions by @ZengyiZhao [here](https://github.com/orgs/modelcontextprotocol/discussions/309) and @wdawson [here](https://github.com/modelcontextprotocol/modelcontextprotocol/discussions/234). Hope we can land this soon!

@dsp-ant @jspahrsummers So, for anecdotal context. What drove me to the discussion leading to this and the PR itself was your [podcast on latent space](https://www.latent.space/p/mcp) with @fanahova and @swyxio Was...

@samsp-msft thanks for the support. PS I raised [a PR to csharp-sdk](https://github.com/modelcontextprotocol/csharp-sdk/pull/360) to change the carrier from `request.params` -> `request.params._meta` (and backfilled a test). I didn't see before that an...

Earlier I mis-attributed `request.params._meta[progressToken]` to BeeAI ACP. It is not BeeAI specific. Rather it is in the [specification already](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/main/docs/specification/2025-03-26/basic/utilities/progress.mdx). So, we already document use of `request.params._meta`, just not generally yet....

@dsp-ant do you have any advice for us on how to progress this PR? I'm happy to revise it, but it seems stalled.

Right now, by naming convention (`Request` and `JSONRPCRequest`) any `*Request` type already implies folks should use `_meta` as described in this PR, just not with the exact guidance. **I suggest...

added a section to the description that it is possible a future JSON-RPC 2.1 could formalize "_meta". That said, I don't expect this to change any current practice. cc @mpcm

going to close this out as it hasn't moved forward in a month. happy to re-open when maintainers are interested in a change. Meanwhile, per the description, there are enough...