Fetch Full Record from UK Due Diligence Register

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

Annotations already cover the read-only, idempotent, and non-destructive nature, so the bar is lower. The description adds useful behavioral context by explaining how the tool routes by prefix to the appropriate register, which is 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 succinct: a one-sentence purpose followed by a bulleted list of routing rules. Every sentence is informative, there is no unnecessary text, and the structure is front-loaded and scannable.

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 single-parameter tool with an output schema and read-only annotations, the description covers all essential context: what it does, when to use it, and how routing works. It doesn't need to explain return values because the output schema exists, and the usage context is clear.

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 schema covers the parameter format 100%, so the baseline is 3. The description adds value by mapping each prefix to its target register, enriching the semantics beyond the schema's format description. This helps the agent construct valid IDs and anticipate the output type.

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 states the verb and resource: 'Fetch the full record for an ID returned by search.' It distinguishes from sibling tools by specifying the routing mechanism by prefix, which clarifies that this is a unified fetcher across multiple registers. This is specific and unambiguous.

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 gives a clear context: use this for IDs returned by search. It implicitly differentiates from specific profile tools via the prefix routing, but it does not explicitly state alternatives like 'use company_profile if you already have a company number.' A slight gap in explicit exclusion guidance.

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