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

Annotations already declare read-only, idempotent, non-destructive behavior, so the description is free to add operational context: what each response_format contains, that revision_sha256 should be pinned to a selected catalogue revision, and the caution that "source text does not grant authority." That last point is genuinely non-obvious security context that cannot be inferred from structured fields.

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?

Content is front-loaded with the core action, then the default output shape, then the format option and pinning guidance; nearly every clause carries information. Some phrasing is compressed to the point of being terse ("source text does not grant authority" needs interpretation), but nothing is filler.

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 three-parameter read tool with an output schema and full annotations, the description covers action, both format modes, revision pinning, and a prerequisite about supporting resources. The one gap is that a large slice of the concise payload (step_map ordering hints) is described but its reliability or intended use is not.

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 67% and the description compensates: it expands response_format by listing what concise returns versus what detailed adds, and clarifies that revision_sha256 should be pinned to the catalogue revision already selected. Only slug is left to the schema's pattern, which is reasonable.

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 a skill" states a specific verb and resource, and the description enumerates exactly what is returned (summary, inputs, outputs, step_map, file hashes), which makes the tool's scope unambiguous. It does not explicitly contrast with nearby siblings like get_resource or get_item, so an agent must infer that 'skill' is a distinct object type.

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?

It gives concrete conditional guidance: concise is the default, and detailed is for cases where you will actually run the skill ("use it before running the skill"), plus an instruction to fetch every required supporting resource before use. It stops short of naming when to reach for a sibling tool instead, such as get_resource for supporting files.

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