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

With no annotations provided, the description fully carries the burden of behavioral disclosure. It goes well beyond a simple definition by mentioning the paid call cost ($0.01 USDC), 24h cache, data minimization, and the specific output fields including risk flags and insolvency cases. This provides a comprehensive picture of the tool's behavior and data quality.

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 description is well-structured and information-dense. It front-loads the key purpose, then uses examples to clarify usage, and includes pricing and caching details without wasted words. Every sentence earns its place, making it both concise and comprehensive.

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?

Given the lack of an output schema, the description must explain return values, which it does by listing fields for both search and profile modes. However, it omits details about the 'limit' parameter's behavior (e.g., default, max) and does not address edge cases like providing both 'q' and 'number'. This leaves minor gaps in completeness.

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 schema has 0% description coverage, so the description must compensate. It explains the 'q' parameter (search query) and 'number' parameter (profile lookup) with examples, but it does not explain the 'limit' parameter, which is a gap. Thus, it adds meaning for most but not all parameters, leaving the description partially compensating.

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 opens with 'Official UK Companies House data in one paid call,' which clearly states the tool's purpose and resource. It then distinguishes between search and profile modes with concrete examples, making it easy to understand what the tool does and how it differs from the sibling tools for other countries.

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?

The description provides clear usage context by showing example queries for both search and profile, and implicitly indicates when to use this tool (for UK company data). However, it does not explicitly state when not to use it or name alternative tools, so it lacks explicit exclusions but has clear enough context.

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