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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is structured. The description adds something annotations cannot: a trust/behavioral caveat that returned content is source material to review rather than instructions to execute, which is genuinely valuable for an agent ingesting third-party text. It stops short of covering failure behavior for an unknown or unpublished slug, so it is not a 5.

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 filler, with the functional statement front-loaded and the safety caveat immediately after. Every clause earns its place and nothing is repeated from the schema or annotations.

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 an output schema present, the description need not explain return values, and it correctly focuses on what is fetched and how to treat it. Given a single documented parameter and full annotation coverage, only edge cases (unknown slug, unpublished skill) are unaddressed.

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 description coverage is 100% and the single slug parameter is fully documented in-schema, including its pattern, max length, and provenance from search_echoo_skills. The description adds no further meaning about the identifier format or lookup semantics, so the baseline 3 is appropriate when the schema carries the load.

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?

"Retrieve the published instructions for one catalog skill" names a specific verb (retrieve) and a specific resource (published instructions for a single catalog skill), and scopes it to one item. It is not tautological and is clearly distinguishable from catalog-search or pricing/documentation siblings, although it never names the sibling it complements (search_echoo_skills appears only in the schema, not the description).

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 second sentence gives meaningful usage framing for the retrieved content (review as source material, do not auto-execute), which implicitly tells the agent how to act after the call. However, there is no explicit when-to-use versus alternatives such as search_echoo_skills or get_echoo_documentation; the search-to-fetch workflow must be inferred from the slug parameter description in the schema.

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