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

With no annotations, the description takes full responsibility and delivers rich behavioral detail: decoded control types, ECCTA verification status semantics, the difference between pending/unknown/overdue, corporate entities lacking verification fields, exemption detection for listed PLCs, and 24-hour caching. This goes well beyond a mere 'returns data' statement.

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 long but every sentence adds operational value: thresholds, decoding, verification semantics, corporate PSC differences, exemptions, and caching. It is front-loaded with the core purpose and then builds logically through data categories and status meanings with 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?

Given there is no output schema, the description compensates thoroughly by specifying the types of PSCs, the fields on each, the meaning of verification statuses, and caching behavior. It gives the agent enough information to interpret and use the returned data correctly without over-specifying internal structure.

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?

There is only one parameter and the schema already covers it fully with a pattern, an example, and zero-padding guidance. The description adds context that the company must be UK-based, but most of the parameter documentation already lives in the schema, so the added value is minimal.

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 starts with a specific verb and resource: 'Get the PSC register for a UK company.' It goes on to enumerate exactly what is returned (individuals, corporate entities, legal persons) and the thresholds, making the tool's purpose unambiguous and distinct from sibling tools like get_psc_chain by focusing on the register itself.

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?

It clearly says the tool is for obtaining a UK company's PSC register, which implies when to use it. However, it does not explicitly state when not to use it or compare it against alternatives such as get_psc_chain, leaving the routing decision partially to the agent.

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