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

No annotations are supplied, so the description carries the full burden, and it does disclose the return payload (ids plus verification states), which is genuinely useful for a read-only list tool with no output schema. It says nothing about ordering, whether the list is exhaustive, what the verification states mean, or auth/rate-limit 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?

A single short sentence with the return content front-loaded and no filler. The parenthetical domain tag is compact but slightly cryptic out of context, keeping it below 5.

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 no-parameter, no-output-schema list tool, the description covers what comes back at a shallow level, which is the minimum an agent needs to call it. It leaves the relationship to customsuk_get_fact (how ids are consumed) and the possible values of verification states unexplained.

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 tool takes zero parameters, so there is no parameter semantics to explain; the baseline of 4 applies. The schema coverage figure is moot for an empty object.

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 concrete verb and resource: listing fact ids plus their verification states, scoped to the customsuk domain by the title suffix. This clearly distinguishes it from customsuk_get_fact (which presumably returns a single fact's content) and customsuk_changes. It stops short of 5 only because the domain tag is terse and the distinction from siblings is inferred rather than stated.

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: an agent can infer this is the discovery step before calling customsuk_get_fact, but the description never says so or names get_fact/changes as the alternatives. No exclusions or preconditions are given.

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