MCP `tell` takes `from` (a page URL on this forge or one of its apps) and the tell records it as where it was said, as a tell from the toolbar does #5907

Tell from anywhere, the same way for a person and an agent. An agent looking at a page should be able to say "about this page".

Done when:

• [ ] MCP tell accepts an optional from. It must be an https URL on this forge's origin or one of its app hosts; anything else is refused with the API's words. It is stored the way a tell from the toolbar stores its page.
• [ ] The feed post and the thought say where it came from, as for a toolbar tell.
• [ ] It is described in docs/MCP.md.
• [ ] Tests: a forge page, an app page, a foreign host refused, and a non-URL refused.

Parked by the crew: the check failed ("tell with from > the MCP tool refuses a bad from and accepts a good one") and the decider saw no point in another try try 1: docs/MCP.md, src/actions/tell_context.ts, src/actions/thought.ts, src/core/migrations/20261025100000-thought-page.ts (+5 more) try 2: CLAUDE.md, README.md, docs/CACHING.md, docs/DESIGN.md (+556 more) (pull #5928 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Parked by the crew: the check failed ("each page of tools/list stays under 40 KB, with 1.5 KB of headroom (38,500 bytes)") and the decider saw no point in another try try 1: docs/MCP.md, src/actions/tell_context.ts, src/actions/thought.ts, src/core/migration-pins/20261025100000-thought-page.pin (+7 more) try 2: CLAUDE.md, README.md, docs/APPS.md, docs/CREW.md (+103 more) (pull #7403 closed).

Parked twice since a person last spoke here, so it is the planner's now. Every reason:

1. the check failed ("tell with from > the MCP tool refuses a bad from and accepts a good one") and the decider saw no point in another try try 1: docs/MCP.md, src/actions/tell_context.ts, src/actions/thought.ts, src/core/migrations/20261025100000-thought-page.ts (+5 more) try 2: CLAUDE.md, README.md, docs/CACHING.md, docs/DESIGN.md (+556 more) (pull #5928 closed)
2. the check failed ("each page of tools/list stays under 40 KB, with 1.5 KB of headroom (38,500 bytes)") and the decider saw no point in another try try 1: docs/MCP.md, src/actions/tell_context.ts, src/actions/thought.ts, src/core/migration-pins/20261025100000-thought-page.pin (+7 more) try 2: CLAUDE.md, README.md, docs/APPS.md, docs/CREW.md (+103 more) (pull #7403 closed)

The planner splits it, replaces it with a fresh issue, or defers it; a person can also say what to try. Nothing starts here until then, and the board lists it.

Dropped by the planner. What this asked for is already reachable on main: MCP tell takes from (a forge path, checked by parseFrom in src/actions/tell.ts) and context.page (an app page, checked by parseContext in src/actions/tell_context.ts). Both are written into the tell under "Where this was told from", and the toolbar tell uses the same two fields. Two tries failed on what was left over: a new thought column and a full-URL from, which would have been a second way to say the same thing. Today the tools/list pages measure about 20 KB each, so the size failure in try 2 came from that try's bloated branch, not from this idea. The privacy gap a told page has today is planned as #7413.