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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds useful context beyond annotations: the result is scoped to the caller's organization, only enabled skills are returned, and it lists the exact returned fields. This is solid disclosure for a zero-parameter read-only tool.

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 compact and front-loaded: the first sentence states the core action and scope, the second clarifies sibling relationship, and the final sentence discloses return fields and read-only behavior. Every sentence adds necessary information without 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?

Given zero parameters, no output schema, and robust annotations, the description is nearly complete: it defines scope, return fields, and sibling differentiation. It could add minor details such as pagination or ordering, but nothing essential is missing for an agent to select and invoke the tool correctly.

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 has zero parameters and 100% schema description coverage, so there are no parameter details to document. Per the zero-parameter baseline, a 4 is appropriate; the description also clarifies the implicit filtering dimension (kind=skill), which is the closest thing to parameter semantics here.

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 names a specific verb and resource: 'List the skill capabilities in the unified capability plane.' It further distinguishes itself from list_capabilities by explicitly saying it is 'list_capabilities narrowed to kind=skill,' and enumerates the returned fields, so an agent can identify the tool without opening sibling schemas.

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 gives explicit routing guidance: it states this tool is list_capabilities restricted to skill, and it names the siblings for mutating operations ('Use enable_skill to add one and disable_skill to remove one'). This clearly tells an agent when to choose this tool versus the alternatives.

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