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

Annotations already cover the read-only/idempotent/no-destruction profile, and the description goes well beyond them: notes are not part of the law, not endorsed by Parliament, written for the Act as enacted and never updated for amendments, HTML-only with no XML feed, and coverage may be grouped or absent per section. These are exactly the caveats an agent needs to avoid citing notes as law.

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?

Dense but front-loaded: the identity and the law-vs-commentary caveat come first, and every following clause (section behavior, availability exceptions, amendment staleness, source format) carries distinct decision-relevant information. It is longer than typical but has little filler.

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?

With no output schema, the description still conveys the return shape (overview plus table of contents vs. single-section commentary) and the data-source limits. Given the read-only annotations, nothing an agent needs to call this correctly is missing.

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 baseline is 3, but the description adds real behavior: passing section returns commentary just for that section, while omitting it returns an overview plus the notes' own table of contents. That return-shaping difference is not stated in the schema and materially informs the call.

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 precise verb and resource ('Read the Explanatory Notes for a UK Act') and immediately defines what the resource is (plain-language government commentary on a section's intent). It explicitly distinguishes itself from the sibling get_legislation_section, so an agent can separate the two without opening either 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?

Gives explicit when-to-use ('use for context on intent'), explicit when-not ('never as the text of the law itself'), and names the alternative tool for that case. It also documents availability conditions up front (Appropriation, Consolidated Fund, Finance and Consolidation Acts never get notes), which prevents futile calls.

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