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

Annotations already declare read-only, idempotent, closed-world, non-destructive behavior, so the description's added value is the permanence guarantee that a resolved version is retrievable even after supersession or withdrawal. It also enumerates the returned content (values, effective dates, citation, verification record and status today) and adds a 'not legal advice' disclaimer. What is missing is behavior on an unknown/unknown-format id, which the annotations do not cover either.

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 permanence guarantee and the returned-content list are front-loaded in the first sentence, and the practical uses follow immediately. The opening sentence is heavily clause-stacked with commas and colons, which slightly hurts scanning, but no sentence is 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 one fully documented parameter, no output schema, and annotations covering the safety profile, the description supplies everything an agent needs: input provenance, the immutability semantics that make this tool distinct, and a summary of what comes back.

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 schema already states that version_id is a version id from a rule response's `id`, including the same example format. The description reinforces provenance and the `rv_…` prefix but adds no meaning beyond the structured field, so the baseline 3 applies.

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?

The description names a specific verb and resource ('Get exactly the version a stored id names') and pins the scope with a differentiator that separates it from date-based siblings: 'forever, even after it was superseded or withdrawn.' An agent can tell this resolves a stored version id rather than fetching a rule by date (get_rule_as_of) or its history (get_rule_history).

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?

It gives concrete when-to-use scenarios ('re-check the value a decision relied on', 'show an auditor which rule applied') and explains where the input id comes from. It stops short of naming which sibling to use instead when you don't already hold a version id, so an agent must infer the alternative from the other tool names.

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