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

Annotations already declare readOnlyHint=false and destructiveHint=true, but the description adds crucial behavior: elapsed time is kept as a time entry, sub-30-second timers are dropped as accidental clicks, and it reports when no timer was running. It does not contradict the destructive hint; it clarifies what is actually destroyed and what is preserved.

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 tightly written sentences, front-loaded with the core action, then the edge case, then the no-timer response. Every sentence earns its place with no filler.

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 parameterless mutation with no output schema, the description covers the action, the outcome, the 30-second edge case, and the no-timer state. Annotations carry the safety profile, and nothing needed for correct invocation is missing.

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?

The tool takes zero parameters, so parameter semantics are not applicable. The baseline of 4 is appropriate, as there are no arguments whose meaning needs explanation.

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 states a specific verb ("Stops") and resource ("the user's running timer") plus the outcome (keeps elapsed time as a time entry). This clearly distinguishes it from siblings like start_timer and get_running_timer.

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 context of use is clear from "Stops the user's running timer" and the no-timer response, but it does not explicitly name alternatives such as checking with get_running_timer first or manually logging time via log_time. No exclusions are provided, so this is clear context without full routing guidance.

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