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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered by structured data. The description adds only the filtering context; it says nothing about whether this is a static reference list, its ordering, or whether callers need any library setup first.

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?

A single short fragment with the resource and its use front-loaded, zero waste. It is terse enough that it reads slightly under-specified rather than polished, but every word earns its place.

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 zero-argument reference lookup this covers the essentials, but there is no output schema, so the description is the only source of return-shape information and it never says whether results are names, ids, or objects — details an agent needs to build a filter for list_library_exercises.

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 tool takes zero parameters, so the baseline is 4. The description correctly implies no input is needed, leaving nothing about parameters to mislead an agent.

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 names the resource (body parts) and its concrete function as filter values for list_library_exercises, so the agent knows what it gets and why. It does not differentiate from the nearby sibling list_library_muscles, which could look like an alternative source of the same filter.

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?

Usage is only implied: the phrase "used to filter list_library_exercises" suggests calling this before/alongside that tool, but there is no explicit 'use when' statement, no statement that it takes no arguments, and no guidance on choosing between body parts and muscle-based filtering.

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