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

The annotations already set readOnlyHint=true, and the description adds genuinely useful context beyond that: it confirms the tool does not block publish/deploy and clarifies the version-wide scope. It aligns fully with the annotation and reveals no side effects. It does not elaborate on error behavior or empty-version cases, but the read-only safety profile is well covered.

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?

Three sentences, each carrying load: the purpose plus read-only caveat, the version-wide scope, and the output-content/next-step guidance. No filler or repetition — well front-loaded.

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 2-required-param read-only tool, the description is notably complete: it compensates for the absent output schema by explaining what each entry contains (inferred type, suggested name, reference location), and the annotations cover safety. The only minor gap is that it does not describe empty-result or error behavior, which is a small omission given the simple input surface.

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% — each of the two parameters already has a concise description ('Policy group ID', 'Version ID'). The description only adds marginal param meaning by tying versionId to 'a version's rules' and noting version-wide coverage, so it stays at the schema baseline of 3.

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 states a specific verb and resource: 'List facts referenced by a version's rules but not yet defined.' The 'not yet defined' qualifier clearly distinguishes it from sibling lexq_facts_list (defined facts) and lexq_facts_create (registering facts), with no need to open schemas.

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 description gives clear context for when to use the tool (checking a version for unregistered facts before or after edits) and explicitly routes the follow-up action to lexq_facts_create to enable type validation and dry-run analysis. It does not explicitly contrast with lexq_facts_list for already-defined facts, leaving that distinction implicit in 'not yet defined.'

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