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

With no annotations, the description carries the full burden, and it usefully discloses that the tool refuses with do_not_answer on drifted or unverified data and never guesses. That is valuable behavioral context, but it says nothing about the success response shape or the fact_id format, leaving the failure path the only fully described behavior.

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?

Two short sentences with zero waste; the core action is front-loaded and the refusal behavior follows immediately as supporting context.

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 simple one-parameter tool with no output schema, the description covers the action and the refusal semantics, but omits how to obtain a valid fact_id and what a successful result contains. That leaves a meaningful gap for an agent trying to call it correctly on the first attempt.

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 fact_id parameter has 0% schema description coverage, so the description must compensate and it largely does not. It implies the id selects one fact from the pensionuk pack but gives no format example or hint that ids come from pensionuk_list_facts.

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 and resource ('Get one verified fact') scoped to the pensionuk pack, and the singular 'one fact' implicitly contrasts with the pensionuk_list_facts sibling. It does not explicitly name the sibling, but the domain-scoped naming makes the distinction clear.

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?

Usage is only implied: fetch a single fact by id. There is no explicit guidance on when to use this versus pensionuk_list_facts or pensionuk_changes, and no prerequisite about where the fact_id comes from, leaving the agent to infer the workflow.

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