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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is fully covered. The description adds the formula families available (standard vs age-adjusted), which is useful framing, but for a pure deterministic calculation there is little else to disclose beyond what annotations and the output schema provide.

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 short sentences, front-loaded with the core action. The 'Returns: {max_heart_rate}' clause is largely redundant given an output schema exists, costing a little space, but nothing else is padded.

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 deterministic calculator with full schema coverage, rich annotations, and an output schema, the description covers purpose and available formulas adequately. The 'sante' bundle cross-reference is vague and the boundary against heart-rate-zone tools is unstated, leaving a small gap.

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%: age (1-120 years) and the formula enum with its standard/tanaka/gulati explanations are documented in the schema itself. The description echoes 'standard or age-adjusted formulas' without adding syntax, units, or edge-case behaviour, so baseline 3 applies.

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 ('Estimate maximum heart rate') and names the formula family, so the agent knows exactly what is computed. It does not, however, distinguish itself from near neighbours such as calculate_heart_rate_zones, calculate_training_zones_running, or calculate_vo2max, which share the cardiac-fitness domain.

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 statement of when to use this tool versus the many adjacent cardiac/fitness calculators, nor any prerequisite or exclusion. The only routing hint is 'See list_bundles for related sante calculators', which points at a discovery tool rather than explaining selection.

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