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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description still adds real behavior beyond that — the exact payload components, the existence of a remediation prompt explaining "what to change when it fires," and the fuzzy-match fallback on unknown ids. It does not describe output format or failure modes beyond the near-miss suggestion.

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 tight clauses, front-loaded with the verb and resource, then the return contents, then the edge-case behavior. Every phrase earns its place and nothing repeats the schema.

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 read-only single-entity lookup with no output schema, the description covers what is returned (naming the sections) and the unknown-id path, which is enough to call it correctly. The remaining gap is sibling disambiguation against the several other rule-related tools.

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 `context` parameter carries an unusually thorough description (why you are asking, never used to rank). The description only reinforces "by id" and implies the `rule` value is a rule identifier; it adds no syntax or format detail beyond the schema. Baseline 3 applies when the schema does the work.

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?

Specific verb ("look up") plus resource ("one rule by id") and an enumeration of what comes back: description, severity, given/then, reference, plus a remediation prompt. It is unambiguous what the tool returns, though it never distinguishes itself from neighbors like explain_rule_result or document_ruleset, which plausibly also surface rule content.

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 one usage signal is implicit: use it when you have a rule id, and it will "suggest close matches for an unknown id" — an unstated fallback for lookup by fuzzy name. There is no explicit when-to-use versus explain_rule_result (rule result interpretation) or document_ruleset, so the agent must infer the routing.

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