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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description goes beyond them by disclosing the field set the agent will receive and the error behavior for unknown ids ('return an error rather than a guess'), which is real behavioral context not encoded in the annotations.

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, zero filler. The usage precondition is front-loaded and the returned-field list is packed into a single clause rather than sprawling bullets.

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 compensates by enumerating the returned fields, and it covers the pre-call requirement, the safety profile, and the failure mode. An agent has everything needed to call it correctly and interpret the result.

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?

There is a single parameter and schema coverage is 100%, including a concrete example ('gas-safety-annual-check'), so the baseline is 3. The description restates where the id originates (search_rules) but adds no format, validation or lookup semantics beyond the schema.

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 and resource ('get ... its full detail') and enumerates the concrete fields returned: requirement, deadline, evidence, penalty, legal basis, guidance links. It is clearly the single-record counterpart to the sibling search_rules, 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?

The opening clause 'Use when you have a rule id from search_rules' gives the exact precondition and names the sibling that produces the input, implicitly excluding search_rules itself as the tool to call here. Nothing about when to invoke this is left to inference.

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