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

With no annotations, the description carries the full burden and does disclose a genuinely non-obvious behavioral trait: the tool returns a 'do_not_answer' refusal rather than guessing when a fact is drifted or unverified. What is missing is the shape of the successful response and the behavior for an unknown or malformed 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, zero waste, with the core operation front-loaded and the safety behavior second. Nothing is repeated from structured fields.

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?

There is no output schema and no annotations, so the description should explain returns and the id source; it covers the refusal behavior but not the success shape or where fact_ids come from. Adequate for a minimal single-parameter lookup, but with clear gaps.

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?

Schema description coverage is 0% for the single required parameter fact_id, and the description adds no meaning beyond the name: no format, provenance (where to obtain valid ids), or behavior on invalid input. The description leaves the only parameter entirely undocumented.

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 states a specific verb and resource ('Get one verified fact') and scopes it to the goodsuk pack, which distinguishes it from the other domain get_fact siblings. It does not explicitly contrast with goodsuk_list_facts or goodsuk_changes, so sibling differentiation is only partial.

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 when you already know which one. There is no explicit guidance on where a fact_id comes from (presumably goodsuk_list_facts) or when to prefer goodsuk_changes instead. An agent must infer the retrieval workflow.

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