Stop timer

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

No annotations are provided, so the description carries the burden of behavioral disclosure. It clearly states the read/write effects: stopping, logging an entry, returning duration/money/new entry ID, and doing nothing when no timer is running. It doesn't detail the rate calculation, but the mentioned return values and edge-case behavior are solid.

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 sentences front-load the core action and result, then cover the failure/no-timer case and the exact return values. Every sentence earns its place and there is zero 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 one-optional-parameter tool with no output schema, the description is complete: it explains what happens, what is returned, and the behavior when no timer is running. An agent has enough information to call it correctly without opening the schema.

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 input schema covers 100% of the single parameter with an 'Optional note stored with the entry' description. The tool description adds no extra nuance about the note parameter, but it doesn't need to because the schema already documents it fully.

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 and resource: 'Stop the running timer and log it as one entry.' It also distinguishes itself from sibling tools like timer_start and timer_status by describing the stopping/logging behavior and the no-op case.

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 gives clear context for use: it applies when a timer is running, and explicitly states what happens when none is running ('says so and writes nothing'). It does not explicitly name alternatives like timer_start or timer_status, so it stops short of a full 5.

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