Get Body Composition

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the agent knows this is a safe read operation that may return partial data. The description adds that it returns measurements plus the average, which is useful. However, it does not disclose details like whether data may be missing for some days, how averages are computed, or if the tool returns empty results when no data exists. With annotations covering the safety profile, a 3 is appropriate.

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 a single sentence that is concise and front-loaded with the key purpose. It lists the specific measurements and the average, with zero waste. It is appropriately sized for a simple read tool.

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 (2 optional parameters, no output schema, read-only annotations), the description is complete enough. It states what data is returned (measurements and average) and the period concept. It does not need to explain return values since there is no output schema, and the annotations cover safety. The only minor gap is not specifying behavior when no data exists, but that is not critical for a read tool.

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 schema already documents both parameters (days and endDate) with their constraints and defaults. The description adds the concept of 'over a period' and 'average across the period', which aligns with the parameters but does not add new syntax or format details beyond the schema. Baseline 3 is correct when schema does the heavy lifting.

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 the tool retrieves body composition measurements (weight, BMI, body fat, muscle and bone mass) over a period and includes the average. The verb 'get' plus the specific resource 'body composition' and the scope 'over a period' distinguishes it from sibling tools like get_weigh_ins, which focuses on weight entries, and get_health_metrics, which is broader.

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 for retrieving historical body composition data over a specified period, with the average included. It does not explicitly state when not to use it or name alternatives, but the context of 'over a period' and the parameter definitions (days, endDate) provide clear context. Sibling tools like get_weigh_ins might be alternatives for weight-only data, but this is not mentioned.

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