small: Trim the costliest MCP tool descriptions to leave headroom under the size ceilings #11426

This pull trims the five costliest MCP tools (limits, spawn, plan, explore, pinned_forge) and leaves the ceilings alone. The mcp-* tests (895) pass, as do tsc --noEmit and scripts/gate.ts. I did not measure how many bytes tools/list dropped, so I can't say how much headroom this bought.

What changed

• limits: the key argument no longer lists all 30 limit names. It is a plain string with a max length. The tool still refuses an unknown key with no_such_limit, and calling it without a key still lists every limit with its bounds. That enum was the single largest cost in the list. The description is also shorter.
• spawn, plan, explore, pinned_forge: argument descriptions are shorter, and explore no longer sets a max length on since. Only the schema wording changed, not any behaviour.
• docs/MCP.md: the table is regenerated with bun scripts/mcp-table.ts.

What I left out

• No tool was added or merged. The explore query alias stays, since removing it would drop behaviour.
• limits no longer advertises its valid keys in the schema; a harness has to call limits with no arguments to see them.

How to try it

• Run bun test test/mcp-size.test.ts test/mcp-table.test.ts.
• Compare the regenerated tool table in docs/MCP.md.

Closes #11420

This pull trims the five costliest MCP tools (limits, spawn, plan, explore, pinned_forge) and leaves the ceilings alone. The mcp-* tests (895) pass, as do tsc --noEmit and scripts/gate.ts. I did not measure how many bytes tools/list dropped, so I can't say how much headroom this bought.

What changed

• limits: the key argument no longer lists all 30 limit names. It is a plain string with a max length. The tool still refuses an unknown key with no_such_limit, and calling it without a key still lists every limit with its bounds. That enum was the single largest cost in the list. The description is also shorter.
• spawn, plan, explore, pinned_forge: argument descriptions are shorter, and explore no longer sets a max length on since. Only the schema wording changed, not any behaviour.
• docs/MCP.md: the table is regenerated with bun scripts/mcp-table.ts.

What I left out

• No tool was added or merged. The explore query alias stays, since removing it would drop behaviour.
• limits no longer advertises its valid keys in the schema; a harness has to call limits with no arguments to see them.

How to try it

• Run bun test test/mcp-size.test.ts test/mcp-table.test.ts.
• Compare the regenerated tool table in docs/MCP.md.

This pull now trims the descriptions of five MCP tools (limits, spawn, plan, explore, pinned_forge) and drops no behaviour or boundary cap. The mcp-* tests (895), test/mcp-size.test.ts and test/mcp-table.test.ts pass, and tsc --noEmit is clean. I did not re-run scripts/gate.ts after this last round. I did not measure the bytes saved, but the size test stays green under the existing ceilings.

Changed after review

• limits: I restored the key enumeration, so a harness sees the valid limit keys in tools/list and no longer has to call limits blind. It was the largest saving, so what remains is only shorter descriptions.
• explore: I restored maxLength: 100 on since, so it is capped like the other search arguments. I also restored the "Unknown word: error" hint on q.
• docs/MCP.md: I regenerated the table with bun scripts/mcp-table.ts.

What stays trimmed

• Wording only. This covers the limits, spawn and plan descriptions, the explore app text, and the pinned_forge version and config text. No tool is added or merged.

How to try it

• Run bun test test/mcp-size.test.ts test/mcp-table.test.ts.
• Compare the regenerated table in docs/MCP.md.