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

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description is consistent with a purely local validation. It adds real context beyond the annotations: no auth key, no cost, and the precise epistemic limit of the result (format/digit only, not existence). Only rate limits and failure modes are unaddressed, which is minor for a free offline check.

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?

Three short sentences with zero filler: capability first, then the negative scope boundary with the named alternative, then the return payload. Front-loaded and easy to scan.

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?

Two required, fully documented parameters, an output schema, and annotations all mean little remains to explain. The description nonetheless covers auth, cost, scope limits and the result fields, which is more than enough for a tool of this complexity.

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 coverage is 100%, so the baseline is 3; the description earns a notch more by noting that left-padding zeros may be completed and that a formatted IE is returned, which tells the agent the 'ie' input is normalized rather than taken verbatim. It still doesn't spell out accepted punctuation formats beyond what the schema already says.

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 and resource: it checks the format and check digit of an Inscrição Estadual for a given UF. It immediately delimits scope against the sibling consultar_ie by saying it does not answer existence/active/ownership, so an agent can pick between the two without opening either schema.

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?

Explicitly names the alternative (consultar_ie) and the exact condition that selects it: real-world existence, status and ownership questions. It also gives preconditions in the negative (no key needed, no charge), leaving nothing to inference about when this tool is the right call.

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