get_fitness_metrics

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

With no annotations, the description carries full burden for behavioral disclosure. It explains the output content (VO2 max, fitness age, race times) and the date parameter defaults, but does not mention side effects, required permissions, data freshness, or error conditions. Adequate but lacks depth.

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 concise with a brief summary followed by an Args section. It avoids unnecessary words. However, the Args block somewhat duplicates information already present in the schema (though adds format context). Overall well-structured 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?

Given the presence of an output schema (return value details not needed in description), the description adequately covers the tool's purpose. However, it lacks information about edge cases (e.g., no data for the given date), potential errors, or the relationship between the date and race predictions. Could be more complete.

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 schema has zero description coverage, but the function description includes an Args block that explains the 'date' parameter's format (YYYY-MM-DD) and default (today). This adds significant semantic value beyond the schema's type definition. The explanation is clear and helpful.

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 specifies that the tool retrieves VO2 max (running and cycling), fitness age, and predicted race times for 5K, 10K, half marathon, and marathon. It uses specific verb+resource structure and distinguishes itself from sibling tools (e.g., strength workouts, sleep) by focusing on fitness metrics.

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 fitness metrics like VO2 max and race times are needed, but it does not provide explicit guidance on when to use this tool versus its siblings, nor does it state conditions or alternatives. No 'when to use' or 'when not to use' directives are present.

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