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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), and the description adds a genuinely new behavioral trait: the pricing/auth model ('Free within the daily allowance, then $0.001 USDC per call via x402'). That is valuable context beyond structured fields, though return-shape behavior is left to the output schema.

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 tight sentences, front-loaded with the core purpose, and each sentence carries distinct information (scope + pricing). No waste.

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 values need no explanation, and the pricing model is disclosed. For a low-complexity single-optional-param tool this is nearly complete; the only gap is not directing the agent to uk-legislation__types for valid type codes.

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 the schema already documents the single 'type' parameter. The description adds only that the filter is optional and refers to 'one type', without enumerating valid type codes or pointing at the sibling that lists them. Baseline 3 is appropriate.

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 resource and scope: 'The newest Acts and instruments published, optionally of one type.' An agent can tell it returns the latest legislation rather than search or a specific item. It does not, however, explicitly distinguish itself from close siblings like uk-legislation__changes or uk-legislation__search.

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?

Only implied guidance ('optionally of one type') suggests a filter is available. There is no statement of when to use this versus uk-legislation__search, __changes, or __types, and no prerequisites or exclusions are given.

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