stop_timer

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the primary action (stop timer) and return value, but does not disclose edge-case behavior, such as what happens if no timer is running, whether the action is destructive/canceling any pending time entry, or the format of the 'time spent' return value. This is a significant gap for a mutation tool with no annotation coverage.

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 a single, concise sentence that directly states the action and return value with no extraneous content. Every word contributes to meaning, making it appropriately sized and front-loaded.

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 simple tool with no parameters and no output schema, the description covers the core function and return value, but lacks completeness regarding error cases and behavioral details beyond the primary action. It is minimally viable but does not fully inform the agent about potential failure modes or nuances.

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 has zero parameters and the schema is empty, so the description does not need to explain parameter semantics. The baseline of 4 applies because there are no parameters to describe, and the description adds no redundant parameter information.

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 uses a specific verb ('Stop') and resource ('currently running timer') with a clear outcome ('return time spent'). It distinguishes itself from siblings like start_timer and get_current_timer by denoting the opposite action (stopping vs. starting) and the addition of returning elapsed time.

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 usage context is implied: it is for stopping the currently running timer. However, there is no explicit guidance on when to use it versus alternatives (e.g., when not to use, or that it requires an active timer). The presence of sibling tools like start_timer and get_current_timer provides context, but no explicit exclusions are given.

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