stop_timer

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

The description adds behavioral context beyond annotations. It explains that stopping an already-stopped timer updates ended_at (non-idempotent if different timestamps), the wire shape (PUT with flat body), and raises 404. Annotations provide readOnlyHint false, destructiveHint false, idempotentHint false, which are consistent and basic; the description enriches them with specific behaviors.

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?

The description is concise: three sentences cover main action, parameter details, wire shape, and error condition. Every sentence adds value without repetition. It front-loads the primary purpose and follows with essential details, making it efficient for an agent to parse.

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?

Given the tool's simplicity and the presence of an output schema (presumably documenting return fields), the description covers inputs, behavior, error handling, and wire shape. It is largely complete but could explicitly mention that the returned 'TimeTracker' is the updated object after stopping. Still, it provides sufficient context for correct invocation.

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 0%, so the description bears full responsibility. It adds valuable detail for ended_at: 'ISO 8601 timestamp; defaults to current UTC time'. However, for timer_id, it provides no extra explanation beyond the schema's minimum and required status. While timer_id is obvious from context, a fuller description could have specified 'the ID of the running time tracker to stop'.

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?

The description clearly states the tool's action: 'Stop a running time tracker. Returns the stopped TimeTracker.' The verb 'stop' combined with 'time tracker' precisely defines the resource and action, and the return type is specified. This effectively distinguishes it from sibling tools like start_timer (starts), delete_timer (deletes), and list_my_timers (lists).

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?

The description explains usage context: it stops a running timer, and 'stopping an already-stopped timer is harmless' implying it can be used for ongoing or already-stopped timers. It also describes error conditions (404 for unknown or wrong user). However, it does not explicitly contrast with alternatives like delete_timer for removal, but the purpose is clear enough.

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