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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, covering safety and side-effect expectations. The description adds useful context beyond annotations by specifying the fixed count (23) and that it returns slugs with anatomical names, which clarifies the output shape. However, it does not describe pagination or ordering behavior, but that's minor for a simple enumeration.

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 clear sentence that conveys all necessary information without any filler or repetition. It is optimally concise 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?

For a parameterless tool with no output schema, the description fully specifies what the tool returns (a list of 23 slugs with anatomical names). There is no need for additional detail about return values or complex behavior—the tool is inherently simple and the description covers everything.

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 has 0 parameters, and the schema is trivially 100% covered. Baseline for 0 parameters is 4, and the description adds no parameter-specific semantics because there are none to describe. This is appropriate.

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 action ('List'), the exact resource ('all 23 supported muscle slugs'), and the included detail ('with anatomical names'). It distinguishes itself from sibling tools by specifying the fixed count and scope, leaving no ambiguity about its function.

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 the tool is for retrieving the canonical list of muscle slugs when needed, but it does not explicitly state when to use it over alternatives or provide exclusions. Since this is a simple enumeration tool with no obvious sibling alternative, the usage context is implied rather than explicitly guided.

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