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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed-world scope, so the safety profile is fully covered. The description adds nothing beyond that for a pure deterministic calculator — no edge-case behavior for zero/invalid time or unit expectations — but for a stateless calculation there is little more behavior to disclose.

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 compact sentences, front-loaded with the core purpose, and the bundle pointer is short. The return-value enumeration is partly redundant given the output schema, which costs a little.

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 calculator with full schema coverage and a committed output schema, this is essentially complete. The description could drop the return enumeration since the output schema exists and instead use that space for sibling disambiguation.

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 coverage is 100%, so both parameters are already documented with units and minimums, which sets the baseline at 3. The description adds mild value by naming the output units (min/km, km/h) alongside the inputs, but the asymmetry between the two parameters is spelled out only in the schema.

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 ('Calculate running pace') plus the exact inputs (distance and time) and the formula outputs (min/km, km/h). It is clearly distinct from other sports calculators, but it never names or contrasts with close siblings like calculate_swimming_pace, calculate_marathon_splits, or calculate_speed_distance_time, so the agent gets no help disambiguating the cluster.

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?

There is no when-to-use guidance and no stated alternative: the only pointer, 'See list_bundles for related sport calculators', is a discovery hint, not a routing rule. An agent must infer from the name alone whether this or calculate_speed_distance_time / calculate_marathon_splits is the right call.

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