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

Annotations already establish read-only, idempotent, open-world, non-destructive semantics, and the description adds substantial context beyond them: the hybrid cached-register/live-CQC read path, the cap of twelve registered locations, the exact fields surfaced (ratings, five key questions, inspection and report dates), and a full change history since 2 October 2026. This is unusually rich behavioral disclosure.

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 core question is front-loaded in the first clause and every subsequent sentence carries new information rather than repeating the name or title. It is dense and semicolon-heavy, which hurts scannability slightly, but nothing meaningful is padded.

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 only one parameter, no output schema, and no nested objects, the description carries the burden of explaining returns and does so thoroughly: registration status with dates, provider type, location inventory with ratings and inspection dates, and change history. An agent has everything needed to call it and interpret results.

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%, so the baseline would be 3, but the description adds genuine meaning: it reveals the matching precedence (the CQC's own Companies House number first, then registered and former names, then a CQC provider or location id) and that the register is read live after matching. That is more than the schema's flat list of accepted input kinds.

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 opening sentence names a precise question set (CQC registration, ratings, rating changes) over a specific resource, and the rest of the paragraph makes clear it is a care-provider register check, readily distinguished from siblings like sra_check, charity_check and aml_register. No ambiguity about what the tool returns.

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 clearly implied and bounded: 'England only. Organisations and services only, never people.' Those are real exclusions that steer an agent away from misuse. What is missing is any explicit statement of when to prefer this over sibling register tools, so it falls short of a 5.

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