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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed-world profile, so the safety story is covered. The description adds content scope by naming the five model components returned, but says nothing about whether the result is one schema or five, static versus versioned, or how large it is.

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?

A single sentence with no filler, front-loaded with the action and immediately naming the returned components. Nothing could be removed without losing information.

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 no-parameter, read-only lookup with no output schema, the description conveys both the purpose and the payload contents, which is close to sufficient. The only real gap is the shape of the response (single bundled document versus named per-entity schemas), which an agent would need to know to consume it.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline applies. The description correctly implies the call is parameterless and fully determined by the tool itself.

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 ('Return') and a specific resource (the FactLot data model rendered as JSON Schema), and enumerates the model components (Fact, Provenance, SourceRef, Rights, Relationship) so the agent knows exactly what comes back. It is distinguishable from siblings like fact_validate or fetch by resource, though it never explicitly contrasts itself with them.

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?

No explicit when-to-use or when-not-to-use guidance is given; the usage is only implied by the purpose (call it when you need the FactLot structure, presumably before building or validating facts). No mention of a relationship to fact_validate or other siblings that might otherwise be confused with retrieving the schema.

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