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

The annotation readOnlyHint: true already covers the safety profile, so the description adds modest value by mentioning it lists all definitions and includes PII status in the output. However, it does not add further behavioral details such as pagination behavior, rate limits, or response shape, which is acceptable given the annotation coverage.

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 description is three short, purposeful sentences: what it does, what it shows, and when to use it. There is no fluff, and the most important information (lists all fact definitions) is 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 simple, read-only list operation with 3 optional and a well-documented schema, this description is sufficient: it defines the resource, the output highlights, and the primary usage context. It does not explain return envelope, but that aspect is not critical when the schema and annotations carry the rest.

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%: page, size, and keyword all have descriptive text. The tool description adds no additional meaning about parameter behavior, so the baseline score of 3 is appropriate.

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 explicitly states the verb 'List' and the resource 'all fact definitions (input variable schema)', and enumerates the fields returned: key, type, required, and PII status. It distinguishes itself from sibling fact operations like create/update/delete/export by focusing on the listing dimension and the schema nature.

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 an explicit use case: 'Always check this before creating rules.' This is a clear directive for when to call the tool. It does not mention when not to call it or alternatives like lexq_facts_unregistered, but the in-context workflow guidance is solid.

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