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 safety profile is covered. The description adds value beyond that by disclosing the return payload fields and, importantly, the negative outcome ("or that the key was not found"), which an agent needs in order to interpret a failed lookup.

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?

One sentence, front-loaded with the action and then the result content. Every clause earns its place, and the failure case is appended without padding.

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 no output schema, the description carries the burden of describing returns and does so by listing the licence detail fields plus the not-found case. Combined with annotations covering the safety profile, an agent has everything needed to call and interpret this tool.

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 the single parameter already documents the format (OP-XXXX-XXXX), so the schema carries the parameter semantics. The description adds no additional syntax, case-sensitivity, or validation guidance, making the baseline 3 appropriate.

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 and resource ("Checks an Opedd licence key") and goes further by enumerating exactly what is returned. This clearly separates it from siblings such as purchase_license, list_licence_orders, and lookup_content, which either create orders or fetch content rather than validate a key.

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?

Usage is only implied by the verb "Checks" and the required key parameter; there is no explicit statement of when to reach for this tool versus browse_registry, lookup_content, or get_compliance_dossier. No exclusions or prerequisites are given, though for a single-purpose key validator the intent is reasonably inferable.

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