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

With no annotations, the description carries the full burden, and it does disclose two useful behavioral facts: execution is paid and a completed run returns an RVO plus a signed Verification Receipt. However, it says nothing about side effects, auth requirements, idempotency, or what happens on unpaid/failed execution, and "RVO" is undefined jargon.

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 compact sentences with no padding, and the tool name is front-loaded. The density of unexplained acronyms (R/IV, RVO) costs a point on effective clarity even though the length is appropriate.

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 zero-parameter, no-annotation, no-output-schema tool, the description still needs to explain the core semantics: what "extract" does versus "verify," what an RVO is, and what the receipt contains. None of that is present, leaving the agent unable to predict the tool's behavior or output.

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 per the rubric the baseline is 4. There is nothing for the description to clarify beyond what the empty schema already conveys.

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 calls it an "independent evidence-verification primitive for evidence," but the tool is named fact.extract, so the stated action (verify) conflicts with the implied action (extract). It never states a concrete verb+resource outcome and does not distinguish itself from the many verification siblings (claim.check, citation.verify, source.verify, evidence.bundle).

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?

There is no when-to-use guidance whatsoever. With siblings like claim.check, citation.verify, number.verify, and evidence.bundle, the agent has no basis for choosing this tool over any of them, and no prerequisites or exclusions are given.

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