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

With no annotations, the description fully discloses the tool's behavior: it is a read-only search, returns up to 5 results, costs $0.005 per call, and lists output fields (results array with specific properties). It does not mention rate limits or authentication, but for a simple, non-destructive search this is adequate transparency.

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 concise at two short paragraphs, each focused on a single aspect: purpose and output, then cost and return structure. It is well-structured and front-loaded with key information. Minor extra detail ('x402, Base mainnet') could be trimmed but does not harm clarity.

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 no output schema, the description provides the output structure explicitly (results[] with fields). It covers both parameters (via schema), cost, and purpose. It does not mention pagination or whether total_matches is accurate, but for a simple top-5 search with limited parameters, it is fairly complete.

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%, with both parameters (q and limit) having descriptions. The tool description adds little beyond what the schema already says, only reinforcing the 'top 5 matches' concept. It does not provide examples or extra usage nuance, so it adds marginal value over the schema.

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 clearly states the tool finds UK companies by name and returns top 5 matches with company number, name, status, and incorporation date. It mentions 'Taster tier' and contrasts with full profile/verdict, hinting at differentiation from sibling tools like uk_company_profile and uk_company_verdict, though not explicitly naming them. This is clear enough but stops short of explicit sibling differentiation.

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 advises use as a quick, cheap search before paying for full profile or verdict, providing clear context for when to use this tool. It implies alternatives (profile/verdict tools) but does not explicitly state when not to use or list alternative names. The guidance is sufficient for basic understanding of its role.

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