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

Annotations already declare read-only and open-world behavior, so the description's contribution is the cost model: $0.02 per call, paid in USDC on Base via x402. That is genuinely useful pre-invocation context for an agent. It omits rate limits and what happens when both an id and a name are supplied, keeping it off a 5.

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?

A single dense sentence that front-loads the resource and scope, then the lookup keys, then the return contents, then pricing. 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?

With no output schema, the description carries the return-value explanation itself (company, role, dates, company status) and adds the pricing requirement, which is enough for correct invocation. Missing only edge-case behavior such as precedence when both lookup parameters are provided.

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 100%, so the baseline is 3, but the description adds the meaningful relationship that 'name' and 'officer id' are two alternative lookup paths rather than joint inputs. It still does not explain the max parameter's interaction with results, so it does not reach 5.

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 and resource: 'Every UK company a person is or was an officer of (director, secretary, LLP member)', plus the lookup modes (name or Companies House officer id) and the shape of each match. This is clearly person-centric, which separates it from the company-centric siblings like companies_profile and companies_search.

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 'every UK company a person is or was an officer of' framing makes the use case explicit: use this when you have a person and want their directorships, rather than starting from a company. It stops short of naming an alternative tool or stating exclusions, so it falls just under a 5.

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