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

With no annotations, the description carries the full burden and does well: it discloses the side effect (calling records a requirement), the return state ('not-covered'), and the pricing model ('per delta'). It does not describe the shape of the not-covered response beyond its status, but the essential behavioral facts are present.

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 compact sentence with the most decision-relevant fact ('Roadmap probe, not yet served') front-loaded, followed by scope, cost, and call behavior. No filler.

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?

For a stub with one parameter, no annotations, and no output schema, the description covers what the tool would do, what calling it actually returns, and its cost model. It is complete enough that an agent will not misinvoke it expecting real director data.

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 nominally 100%, so baseline is 3, but the schema's only description is the literal string 'company_number' with no added meaning. The tool description says 'per-entity' without ever explaining that company_number identifies the entity being monitored, so it neither helps nor hurts.

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 resource and scope: a per-entity change feed for officer appointments and resignations, and immediately flags it as an unserved roadmap probe. The resource ('officer appointments and resignations') distinguishes it from siblings like uk_company_profile and uk_psc_ubo, though it does not name them directly.

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?

'Roadmap probe, not yet served' plus 'Calling records the requirement and returns not-covered' makes the intended usage explicit: call it only to register demand, not to obtain data. It stops short of naming an alternative tool an agent should use instead for actual director data, so it is one step from a 5.

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