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

With no annotations, the description carries the full burden, and it does describe the informational, read-only payload (register shape, counts, identifier schemes, citation). It omits any note about caching, freshness of the counts, or that the response is a metadata blob rather than entity records — the main residual risk for a zero-param discovery call. The awkward "register register" repetition slightly muddies the register it refers to.

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 content list is front-loaded and the call-to-action is a short imperative sentence at the end, which is the right position for an ordering hint. The single long enumerative sentence is dense and the duplicated "register register" is sloppy, but nothing is 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?

No output schema or annotations exist, so the description must convey return content, and it does enumerate the main buckets (fields, counts, regions, services, identifier schemes, citation). For a simple metadata tool this is nearly sufficient; it just doesn't hint at the structure of the return or how large it is, which matters since there is no output schema.

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 tool takes zero parameters, so the schema has nothing to explain and the baseline is 4. The description correctly implies no filtering or argument is needed to obtain the register-wide overview.

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 the resource (the Roofing Quotes UK register) and enumerates the concrete content an agent gets back: fields, entity counts, regions, services, identifier schemes, and citation guidance. That is specific enough to distinguish it from entity_lookup or entities_search. It does not, however, explicitly separate itself from siblings with overlapping scope such as dataset_columns, dataset_stats, and dataset_provenance, which also surface fields, counts, and citation data.

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?

"Call this first." is a direct, actionable ordering instruction that tells the agent when this tool belongs in a workflow. There is no statement of when NOT to use it or which sibling to prefer for a narrower need (e.g. dataset_columns for a field list alone), so it stops short of full routing guidance.

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