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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuinely useful operational context beyond that: the exact REST mapping (GET /v2/user/measurement/body) and the required OAuth scope (read:body_measurement), which tells the agent what authorization is needed before calling. It does not mention rate limits or caching behavior.

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 sentences, zero waste. The payload (what the user gets back) is front-loaded, and endpoint/scope metadata is compressed into a trailing clause.

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?

With no output schema present, the description compensates by naming the returned fields and their units, and it adds endpoint and scope information. For a zero-parameter read-only tool this covers everything an agent needs to call it and interpret the response.

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?

Zero parameters, so the baseline of 4 applies. The description goes slightly beyond by documenting the units of the values returned (meters, kilograms), which helps the agent interpret results correctly even though those are not parameters.

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+resource (get body measurement) and immediately enumerates the fields returned with units (height in meters, weight in kilograms, max heart rate). No sibling covers body measurement, so the resource name alone disambiguates it from the cycle/sleep/workout/profile siblings.

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 resource name implies when the tool is relevant (whenever the agent needs the user's height/weight/max HR), but there is no explicit when-to-use statement, no exclusions, and no named alternative. Usage is inferable rather than stated.

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