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

No annotations are supplied, so the description carries the full disclosure burden. It does reveal the concrete outputs and their units, which is genuinely useful behavioral context, but it never states that this is a pure, side-effect-free computation, nor that results assume uniform pacing with no elevation, wind, or negative-split modeling.

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 zero filler; the verb and computed outputs lead, and the supported distance list trails. Every clause contributes information the agent would otherwise have to infer.

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 two-parameter pure calculator with full schema coverage and no output schema, the description is nearly sufficient because it enumerates the returned metrics in their units. The only material omission is the even-pace assumption behind the splits, which affects how results should be presented to a user.

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 100%, so the baseline is 3, and the description adds meaning by mapping the accepted distance_km values to named race presets (5K, 10K, Half Marathon, Marathon, custom). That mapping helps an agent translate a user's race name into the numeric parameter, though it adds nothing about target_minutes beyond the schema's own example.

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?

Names a specific verb (Calculate) and resource (race pace splits) and enumerates the exact metrics produced: min/km, min/mile, km/h, and 400m lap time. The supported distance presets are also listed, so an agent knows the scope without opening the schema. There are no siblings to differentiate against, which caps the value slightly.

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 infer it should call this when it needs pace or split figures from a distance and target time. There is no explicit when-to-use statement, no exclusions, and no stated prerequisite that the pace is assumed even (constant speed throughout).

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