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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context by confirming the operation is offline with no network request to legislation.gov.uk, reinforcing the openWorld hint. It does not discuss output size or caching, but with an output schema present that omission is minor.

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?

The content is front-loaded with the core purpose ('decode the vocabulary') and then a dense, information-bearing enumeration of covered tables. It is a single long sentence, but every clause maps to a distinct table the caller can request, so little is wasted.

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 one enum parameter, full schema coverage, an output schema, and clear read-only/idempotent/offline annotations, the description covers everything an agent needs. It comprehensively enumerates the returnable tables and confirms the offline nature, leaving no material gap for a reference-lookup tool.

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 100% and the single enum parameter is fully documented in the schema, which sets a baseline of 3. The description earns above baseline by expanding each enum value into concrete content, e.g. naming the annotation letters (F, C, I, M, E, P, X) and clarifying that 'types' returns labels, categories, and enacted keywords.

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 (decode/list) and resource (the reference vocabulary that other uklaw_* tools consume and produce), and enumerates exactly which tables it exposes. An agent can immediately tell this apart from siblings like uk law_search_legislation or uklaw_get_document, which perform lookups rather than return the shared vocabulary.

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 framing 'Decode the vocabulary the other uklaw_* tools take and return' strongly implies the usage context: consult this before or alongside the other tools to interpret codes. The 'Offline — no request to legislation.gov.uk' note tells the agent it is a local reference call. However, it never states explicit when-not conditions or names a sibling alternative, so it stops short of full routing guidance.

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