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

Beyond the readOnlyHint annotation, the description adds behavioral details: ordering (newest-used first), limit parameter, and the structure of each skill (including steps, counts, version). It also explains the overall workflow (brain reads descriptions then invokes skill). No contradictions with annotations.

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 three sentences that front-load the main purpose and include essential details (return fields, ordering, limit) without extraneous information. Every sentence adds value.

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 simple list tool with one optional parameter and no output schema, the description is remarkably complete. It covers return shape, ordering, limit, and connects to the broader skill workflow (invoke_skill). No gaps relevant to tool usage.

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 input schema already fully describes the 'limit' parameter (max skills, default 20) with 100% coverage. The description does not add extra semantic meaning beyond what the schema provides, so a baseline score of 3 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 tool returns the agent's persistent skill library, listing tool-call sequences saved, sorted newest-first. It explicitly identifies the resource (skill library) and action (list), and distinguishes from sibling 'search_skills' by implying this is for all skills while search is for querying.

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 explains that the brain reads descriptions to find a matching skill and then calls invoke_skill, providing context for use. However, it does not explicitly contrast with search_skills or state when not to use this tool, missing some guidance on alternatives.

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