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

With no annotations, the description bears the full burden. It states the tool calculates and returns zones, implying a read-only computation. However, it does not disclose any behavioral traits beyond the core operation, such as idempotency or side effects. It is minimal but not misleading.

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 extremely concise with two sentences. The first sentence states the purpose, and the second provides additional context about the return and a pointer to related tools. Every word is necessary, and there is no fluff.

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?

Given the tool's simplicity, full schema coverage, and existence of an output schema, the description is fairly complete. It states the input parameter, calculation basis, and output hint. The reference to list_bundles adds context. However, it could briefly mention the number of zones or output structure, though the output schema likely covers that.

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% for the single parameter vma, and the description does not add additional meaning beyond what the schema already provides. The description mentions the output includes vma_kmh, but that is not a parameter. Thus, no added value for parameter semantics beyond baseline.

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 clearly states it calculates 6 running training zones as speed ranges based on VMA. The verb 'calculate' and resource 'running training zones' are specific. However, it does not explicitly differentiate from similar tools like heart rate zone calculators, though it references list_bundles for related calculators.

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 implies usage when VMA is known, but it does not provide explicit when-to-use/when-not-to-use guidance or mention alternatives. The reference to list_bundles for related calculators offers some context but not direct alternatives.

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