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

With no annotations supplied, the description carries the full burden, and it does disclose two useful traits: the data source (OS Open Names) and the per-call cost of 1 credit. It omits behavioral details that matter here — how ambiguous names are resolved, whether multiple matches are returned, and geographic coverage limits — so the disclosure is partial.

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?

A single compact sentence that front-loads the input→output mapping, with the dataset and cost parentheticals trailing where they belong. No wasted words, though the compression is telegraphic enough that a little more structure would help.

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?

There is no output schema, so the description must convey return values — it does list coordinates, county, district, and region, which is the minimum needed. It does not explain the coordinate format, how results are ordered when 'count' > 1, or failure behavior for unknown names, leaving gaps for a 2-parameter lookup 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 description coverage is 100%, so 'query' and 'count' (number 1-20) are already documented in the schema. The description adds no syntax, format, or matching-behavior detail for either parameter, so the baseline of 3 applies.

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?

Names a specific transformation (GB place name → coordinates, county, district, region) and cites the underlying dataset (OS Open Names), which is far more than a restatement of the name. It does not, however, differentiate itself from the obvious sibling postcode_lookup, which an agent could easily confuse it with for UK location resolution.

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?

There is no statement of when to use this versus postcode_lookup or wikidata_lookup, no note that it only covers Great Britain (so non-GB queries will fail), and no guidance on what to do when a place name is ambiguous. The agent must infer all selection logic.

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