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

Annotations already declare readOnly, idempotent, open-world, non-destructive. The description adds genuinely new behavioral context beyond those: a hard cap of the most recent 50 changes, the fields returned (amending provision, in-force dates, whether the change is reflected in the text), and the payment model (free within daily allowance, then $0.003 USDC per call via x402). That pricing/limit disclosure is valuable and not derivable from structured fields.

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 sentences, front-loaded with the resource and its contents before the ancillary payment note. Nearly every clause earns its place; the x402 pricing sentence is relevant for invocation planning even if slightly appended.

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?

An output schema exists, so return-value structure needn't be restated, and the description still summarizes what the response contains. Parameters are covered by the schema and the payment model is disclosed. The only gap is the absence of routing guidance relative to sibling tools.

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 100%, so all three parameters (type, year, number) are already documented in the schema, including the regnal-year edge case. The description adds no parameter-level meaning beyond identifying the target legislation, so the baseline 3 applies.

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: retrieve the most recent 50 changes (substitutions, repeals, insertions) made by later legislation to a given Act/SI, with amending provision, in-force dates, and reflected-in-text status. This is clear and concrete. It does not, however, explicitly distinguish itself from siblings like uk-legislation__provision or uk-legislation__item, so an agent must infer the boundary.

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?

There is no explicit when-to-use or when-not-to-use guidance, and no named alternatives among the uk-legislation siblings (item, latest, provision, search, types). The implicit context — you supply type/year/number to identify a specific piece of legislation — is present but never spelled out as routing guidance.

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