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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint), so the bar is lower. The description nonetheless adds real behavioral context: results are 'cleaned and confidence-ranked' and the data scope is restricted to company-level records, never officer personal data. It omits auth/rate-limit behavior and does not explain what the ranking signal means.

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?

Two short sentences, front-loaded with the core action and immediately followed by the most valuable constraints (source, ranking, data scope). No filler or redundant restatement of the title.

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?

With no output schema, the description carries the burden of explaining returns, yet it only gestures at 'confidence-ranked' without describing result fields or pagination beyond the limit param. Combined with the undocumented q parameter, the definition is serviceable but leaves real gaps for an agent to guess at.

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 coverage is only 50% and the required parameter q has an empty schema description. The description says nothing about what q should contain (company name, registration number, fuzzy matching?) or how limit interacts with ranking, so the most important input is effectively undocumented in both places.

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?

States a specific verb+resource ('Search UK registered companies') and scopes the domain to Companies House company-level data, explicitly excluding officer personal data. It does not, however, distinguish itself from company-adjacent siblings such as public_record, ownership, or charges, so an agent cannot route between them from the text alone.

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 when-to-use guidance and no named alternative. The description never says when this search should be preferred over siblings like public_record or charity_check, nor any preconditions, so the agent must infer usage from the name alone.

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