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

The description adds a real behavioral fact beyond the annotations: stopping is not merely a state change, it creates a booked time entry. However, it does not disclose what happens if no timer is running (error vs no-op), which matters given idempotentHint=false and a side-effecting operation.

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?

A single, front-loaded sentence with no filler that conveys both the action and its consequence.

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 one-parameter tool with annotations covering the safety profile and no output schema, the definition covers the essential action and its side effect. The only gap is the unspecified edge case of stopping when nothing is running.

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?

There is one optional parameter (description) with 0% schema description coverage, and the description never mentions it or explains its effect on the resulting time entry. With such thin schema documentation, the description should compensate and does not.

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?

States a specific verb and resource ("Stop the running timer") plus the side effect ("book the time as a time entry"), which implicitly separates it from discard_timer and get_active_timer. It never names those siblings, so differentiation is inferred rather than explicit.

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?

Usage is only implied: an agent can deduce it should call this when a timer is running and the time should be kept. There is no explicit when-not guidance (e.g., use discard_timer to throw the time away, or get_active_timer to check first) despite several closely related siblings.

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