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

Annotations already declare the tool as read-only, idempotent, non-destructive, and closed-world. The description adds valuable non-annotation context: companies are listed with before/after values while sole traders and partnerships are only counted, and the default release behavior is clarified. No permissions or rate limits are mentioned, but the added output asymmetry is meaningful.

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 front-loaded with the core purpose and then adds behavioral and parameter details. It is dense but every sentence contributes useful information; minor improvements could come from breaking the long first sentence into a clearer list, but it remains efficient.

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 the annotations covering the safety profile and the presence of an output schema, the description need not explain return values. It adequately covers the tool's scope, the default release behavior, and an important output asymmetry for different entity types. Nothing critical is missing for an agent to invoke it 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?

With 60% schema description coverage, the description compensates by explaining the release parameter format (YYYY-MM-DD, default latest, and that data_status lists them) and by enumerating change categories that map to the change_type enum. It does not elaborate on area, limit, or offset beyond what the schema already provides, so it is not fully comprehensive.

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 clearly states what the tool does: it reports changes between consecutive DVSA operator licence files and enumerates the types of changes included. It distinguishes the resource and verb ('what changed between... file and the one before'), though it does not explicitly contrast with sibling tools like new_licences or licences_ended.

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 implied by the description of output and the note that it defaults to the latest file and accepts a release parameter. However, there is no explicit guidance on when to choose this tool over alternatives such as new_licences or area_stats, nor any stated exclusions.

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