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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds 'deterministic' (consistent results) and 'Paid (x402)' (cost implication), which are behavioral traits beyond the annotations. No contradiction with annotations is present.

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 a single short phrase, which is concise, but it is under-specified for a tool with two parameters and nested objects. It is front-loaded but lacks necessary structure or elaboration, making it insufficiently informative for its complexity.

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 tool with no output schema and a nested input schema, the description does not explain return values, prerequisites, or edge cases. It fails to convey what 'counterfactual analysis' returns or under what conditions it should be invoked, leaving the agent without critical context.

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 0%, and the description provides no explanation of the 'subject' or 'counterfactual' parameters. The name 'counterfactual' and the schema field align, but the description doesn't clarify what the counterfactual object should contain or how the CNPJ is used, leaving the agent without meaningful parameter guidance.

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 'deterministic counterfactual analysis' provides a domain-specific noun phrase but lacks a clear verb+resource structure. It doesn't explicitly state what action is performed on the subject or what output is produced, distinguishing it from siblings only by its generic 'analysis' label. It is not a tautology but is vague about the tool's core function.

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 when-to-use guidance or alternatives are mentioned. The phrase 'Paid (x402)' hints at a cost condition, but it doesn't explain scenarios where this tool should be preferred over sibling tools like 'decide' or 'preflight'. There is no explicit guidance on excluding other tools.

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