x402 Trust watch: cancel early

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden and delivers two genuinely useful behavioral facts: cancellation is idempotent, and the watch log remains readable until expiry (i.e. cancel is not a data-destroying operation). It omits error/permission behavior for an already-expired or unknown watch, so it is strong rather than complete.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short clauses, action first, then the two facts that matter most (log retention, idempotency). Every word earns its place and nothing is padded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter mutation with no annotations and no output schema, the description covers the two things an agent most needs: the effect on existing data and safe retry behavior. Minor gaps remain around failure modes and whether a cancelled watch can be renewed or recreated.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and both parameters (watch_id, secret) are documented in the schema, including that the secret is a one-time bearer token from x402_watch_create. The description adds no parameter-level detail, so the baseline of 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

"Stop a watch now" states a specific verb and resource, and the surrounding watch_* siblings (create/edit/renew/events) make the cancel semantics easy to place. It does not explicitly name which sibling to use instead when the intent is to pause or edit, so it stops short of full differentiation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

"Stop a watch now" plus "cancel early" implies the trigger condition (ending a watch before its expiry rather than letting it lapse), but no alternative is named and no prerequisites or exclusions are stated. Usage is inferable, not explicit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.