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

Goes well beyond the readOnly/openWorld/idempotent annotations by disclosing the parallel execution model, the ID-only return shape, and the partial-failure semantics: `registers_searched` vs `registers_unavailable` with `is_partial`, the critical warning that empty ids + is_partial=true means UNRESOLVED rather than 'nothing on record', and that a total register outage raises instead of returning empty.

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?

Front-loads the core purpose in the first sentence, then layers scope, retrieval workflow, and failure semantics in tight, well-organized sentences. Every sentence carries distinct, actionable information 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?

Despite an output schema existing, the description usefully clarifies the return contract (result IDs plus fetch workflow) and fully specifies the partial-vs-unresolved failure distinction. Nothing an agent needs to interpret results or handle degraded register responses is missing.

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?

With a single parameter at 100% schema coverage, the schema already documents that `query` accepts a company name, charity name, director name, or keyword. The description adds no format, syntax, or length guidance beyond what the schema provides, so the baseline 3 applies.

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 (Search) and resource (all UK due diligence registers), enumerating the exact registers covered: Companies House, Charity Commission, disqualified directors, and Gazette insolvency notices. This aggregate scope cleanly distinguishes it from per-register siblings like company_search, charity_search, and disqualified_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?

Clearly establishes the aggregate use case ('search across all registers simultaneously') and the required follow-up workflow: results are IDs, so 'use fetch with each ID to retrieve the full record.' It does not explicitly state when to prefer a narrower sibling (e.g. company_search) over this one, so it stops short of full alternative routing.

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