extend_checkout

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

Goes well beyond the annotations by disclosing the session prerequisite, reliance on the cached checkout_token, and three distinct failure modes, which the agent genuinely needs. The ttl clamp is repeated from the schema, so one of its statements is slightly redundant; still, the failure/session semantics are real added value on top of readOnlyHint/openWorldHint/idempotentHint.

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?

Three sentences, front-loaded with the action and its motivation, then prerequisites, then constraints. No filler and nothing meaningful omitted.

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?

With only two params, full schema coverage, annotations covering the safety profile, and no output schema, the description supplies everything else needed: why to call it, what session state must exist, and how it fails.

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 description coverage is 100%, so the baseline is 3. The description restates the ttl_minutes clamp that the schema already documents and adds no new format, range, or default guidance for task_id or ttl_minutes beyond what is in the schema.

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?

Specific verb+resource ("Push the expiry of an existing checkout_task lock forward") with the motivating condition ("work that runs longer than the original ttl_minutes"). It explicitly ties itself to the sibling checkout_task, so an agent can distinguish it from release_task or checkout_task immediately.

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?

Clearly states when to reach for it (long-running work outliving the original TTL) and enumerates the failure conditions (lock never acquired here, released, or expired). It does not name a fallback tool to use when those conditions hold, so a triggering-the-wrong-tool exclusion is implied rather than explicit.

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