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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful behavior not in the structured fields: the result cap of 10 matches and the exact fields returned (name, company number, status, incorporation date), which matters because there is no output schema.

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 tight sentences with zero filler, front-loading the action and scope before the downstream routing hint. Every sentence carries distinct information (purpose, cost, return shape).

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?

For a one-parameter search with no output schema, the description supplies the return cap and field list an agent needs to consume the result, plus the relationship to the next tool. Nothing required to call or interpret it is missing.

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 100% schema description coverage on a single parameter, the schema already documents the query field and its example. The description adds no format, matching, or disambiguation guidance beyond what the schema provides, so baseline 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?

Specific verb (Search) plus resource (Companies House for UK companies by name) with an explicit scope. It also distinguishes itself from the sibling check_uk_business by naming that tool as the downstream consumer, so an agent can tell the two apart without opening either schema.

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?

Clearly states the context of use: run this first to obtain a company_number for check_uk_business, and notes the call is free. It does not state any when-not conditions (e.g. what to do if you already have a company number), so it falls short of a full 5.

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