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

Annotations are absent, so the description carries the full behavioral burden. It does disclose the output contract ('a verdict and reason') and mentions pay-per-use cost on Base, which is useful. Still, it does not describe the source of the fact-check, confidence, evidence, or any limitations, leaving the agent uncertain about what the verdict will be based on.

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 exceptionally compact and front-loaded. It communicates the action, output, input, and pricing in one short sentence with no wasted filler or redundant detail.

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 one-parameter tool with no output schema, the description covers the essential context: it tells the agent what input to provide and what output to expect (a verdict and reason). It would be stronger if it specified the possible verdict format or language, but it is otherwise complete for practical invocation.

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 schema already provides 100% coverage for the single parameter, describing 'input' as 'afirmación a verificar.' The description only restates this as 'input=claim' and adds no extra format, length, or language guidance beyond the schema.

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 opens with a specific verb and resource: 'Fact-check a claim with a verdict and reason.' This clearly identifies the action, the input kind, and the expected result. It is also distinct from the sibling tools such as code-gen, sentiment, or translate because the task is unambiguously verification-oriented.

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?

Usage is implied rather than explicit: when an agent has a claim to verify, this tool seems appropriate. However, the description never says when not to use it or names an alternative such as research, explain, or inference, so an agent must infer the choice among the many sibling tools.

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