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

Annotations already cover read-only/open-world access, but the description adds genuinely non-structured context: the $0.005 USDC per-call x402 payment requirement, which is critical for an agent to know before calling. It does not state what happens if neither name nor number is supplied, nor any rate limits.

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?

Front-loaded with the source and payload, followed by the two invocation keys and the cost. The field enumeration is long but each item is informative, and there is no filler or repetition.

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 carries the return-value burden and does so with a solid field list; the pricing disclosure rounds it out. It leaves the zero-required-parameter case (call with no arguments) and any result limits unaddressed.

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 only 50% schema description coverage, the description compensates by explaining that both inputs are search keys (company name or company number), which the schema does not state for 'name'. It does not clarify matching semantics (exact vs partial) for the name parameter.

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 resource (UK company records from Companies House) and enumerates the returned data precisely (status, officers, PSC, filings, insolvency flags), so the agent knows exactly what it gets. However, it never distinguishes itself from the closely named sibling uk_companies_search, leaving the routing question open.

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?

'Search by name or company number' implies how to invoke it, but there is no when-to-use guidance and no alternative named, despite heavy overlap with siblings uk_companies_search, uk_officer and uk_filings. The agent must infer which lookup tool to pick.

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