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

With no annotations, the description carries the full burden, and it does disclose real behavior: the tool returns a do_not_answer refusal on drifted or unverified facts rather than guessing. That is valuable beyond structured data, but it omits the success shape (no output schema exists), whether refusal is an error or a sentinel payload, and what happens for an unknown fact_id.

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, front-loaded with the action and scope, then the refusal guarantee. No filler, no repetition of the schema, and every clause adds information.

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 single-parameter read tool with no annotations or output schema, it covers purpose and the refusal contract, which is the most important behavioral caveat. It still leaves the agent without fact_id provenance and without any sense of what a returned fact looks like.

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?

One parameter with 0% schema description coverage, so the description must compensate. 'One verified fact' implies fact_id selects a fact, but the description never explains where a fact_id comes from, its format, or validity rules — leaving the only argument's semantics underspecified.

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 insuranceuk pack, which separates it from the many other domain packs and, via 'one fact', from insuranceuk_list_facts. Differentiation from insuranceuk_changes is only implied, so it falls short of a 5.

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 implied: fetch a single fact by id rather than enumerating. However, there is no guidance on when to prefer this over insuranceuk_list_facts or insuranceuk_changes, and critically no note that fact_ids must first be discovered via insuranceuk_list_facts, which is the main usage pitfall here.

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