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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false. The description adds meaningful behavioral context beyond those annotations: the operation is FREE, returns exactly one result, is deterministic, and includes the exact advertised price. No contradictions with annotations are present.

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 a single, compact sentence that leads with the most operationally important fact (FREE), then states the core behavior and output. Every word earns its place, and there is no filler or repetition of schema/annotation information.

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 read-only single-parameter lookup with strong annotations, the description conveys the key behavioral facts and the return content at a useful level. The main gap is that 'capability definition' is not elaborated, and since there is no output schema, a slightly richer description of what a definition includes would improve completeness. Overall, quite adequate for the tool's simplicity.

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 0%, and the description does not explain the 'name' parameter's meaning, format, or allowed values. The tool name and the word 'capability' imply that 'name' identifies a capability, but the description provides almost no compensation for the missing schema documentation.

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 uses a specific verb ('Returns'), a specific resource ('one deterministic capability definition'), and adds the unique qualifier 'exact advertised price'. This clearly distinguishes it from sibling tools like capabilities.list and capability.quote even without naming them.

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 words 'deterministic' and 'exact advertised price' imply this is the correct tool when you need the advertised price rather than a quote or list, but no explicit when-to-use or alternative guidance is given. The 'FREE' prefix is a useful selection signal, but exclusions and sibling comparisons are left unstated.

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