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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, and the description still adds a genuine constraint not present in structured data: Northern Ireland postcodes are excluded. It also notes that GB postcodes are treated as identifying their area, which is non-obvious behavior for a text search.

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?

Three short sentences, front-loaded with what the tool returns, then the query semantics, then the exclusion. No filler and nothing repeated from annotations or schema.

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?

An output schema exists, so listing page paths, titles and citation URLs is slightly redundant, but the NI postcode exclusion and postcode-as-query behavior make the definition usable as-is. The one gap is the absence of any routing signal against the similarly named sibling search_places.

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 0% for the single 'query' string, so the description must carry the load — and it does, clarifying that the query is a place name and that postcodes are also accepted (GB only). That is materially more than the bare 'string, maxLength 100' the schema provides.

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 ('Find') and resource ('UK area overview documents') plus the query dimension ('by place name'), which is enough for an agent to know this returns documents rather than places. It does not name or explicitly contrast with the sibling search_places, so an agent must infer the split from the phrase 'documents' vs 'places'.

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?

Gives one real usage constraint — GB postcodes resolve to their published area, Northern Ireland postcodes are unsupported — which tells the agent when a query will fail. Beyond that, 'for research' is vague and no alternative (search_places, get_place, lookup_postcode) is named or excluded.

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