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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true, covering safety and idempotency. The description adds value by listing the exact fields returned (accounts due date, charges, insolvency history, etc.), which goes beyond the annotations. No contradictions.

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 a single, well-structured sentence that front-loads the purpose and lists key fields. Every word adds value, with no wasted or redundant content.

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?

The description covers all major aspects of the tool: input, output fields, and data source. Given the simple one-parameter call and the presence of an output schema, it is sufficiently complete for an agent to understand usage and expected results. Minor omission: no mention of error handling or edge cases.

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?

The single parameter 'company_number' is well-described with examples (Barclays, Tesco) and a source hint ('Get from search results'). Schema coverage is 100%, so the description adds meaningful context beyond the schema's basic type and description.

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 clearly specifies the verb ('details') and resource (UK company by Companies House number) and lists the specific fields returned (name, type, status, SIC codes, etc.). It is distinct from the sibling tool 'business.ukcompany.search' which searches by name.

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 description implies use when a company number is available, and the parameter description suggests getting the number from search results. However, it does not explicitly state when to use this tool versus the search sibling or other alternatives. The context of sibling tools provides some guidance.

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