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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower; the description still adds real value by disclosing immutability semantics, the head-vs-snapshot resolution rule, and that the payload contains complete skillMarkdown plus metadata.

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?

Four tight sentences, front-loaded with the verb and key, then version semantics, then return shape, then the boundary against publishing. No filler and nothing buried.

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 two-parameter read tool with a full output schema, annotations covering safety, and a closed-world hint, the description supplies everything needed to invoke correctly: key format, version semantics, and the scope boundary.

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 coverage is 100% and both property descriptions already spell out kebab-case slug format and the head-vs-version behavior, so the description largely restates structured data. It adds contextual framing but no syntax or constraint the schema lacks, so baseline 3 is right.

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 (returns) plus resource (one immutable public Agent Skill) and pins the lookup key (exact lowercase slug, optional x.y.z version). The singular 'one' and the mention of a separate publishing endpoint distinguish it from list_agent_skills and any write counterpart.

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?

Explains the two retrieval modes clearly: omit version for the current published head, supply version for that immutable snapshot. It also steers publishing away to a separate authenticated endpoint, giving one explicit exclusion, though it never names list_agent_skills as the discovery alternative.

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