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

No annotations are provided, so the description carries the full burden. It discloses the legal basis, the effective date (1 January 2026), and a non-obvious behavioral rule—announced extensions remove the charge entirely rather than deferring it—though it does not state that the tool is side-effect-free or describe validation/error 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?

Two tightly written sentences with no wasted text. The legal basis and charge outcome are front-loaded, followed by the key 2026 proviso.

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 seven-parameter legal calculator with no output schema and no annotations, the description lacks return-value detail (e.g., amount format, currency, breakdown) and does not explain parameter interactions. It gives useful legal context but is not fully complete.

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 coverage is 71%, with most parameters documented in the schema itself. The description does not map its 'two provisos' language to specific parameters or add syntax beyond what the schema already provides, so the baseline score of 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 verb ('Apply article 50A ... and return the charge') and a precise resource (late filing or late payment charge), with the 2026 provisos further narrowing scope. An agent can identify the tool's function without opening the schema.

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?

The description implies the scenario (late filing or late payment), but it does not explicitly say when to use this versus alternatives or note exclusions/prerequisites. No sibling tool overlaps, so the choice is fairly clear, but guidance is inferred rather than stated.

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