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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety is covered. The description adds context about the specific information returned (exemptions, NFS-e, FX rules, crypto prohibitions), but does not disclose additional behavioral traits like response size, error conditions, or performance.

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 two sentences: one stating the tool's purpose and returns, another for usage guidance. It is front-loaded with key information and contains no redundant or extra words.

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?

Given the low complexity (1 parameter, full schema coverage, output schema exists), the description adequately covers purpose, returns, and usage. It does not detail output structure, but the output schema handles that. Minor gap: could mention that queries are read-only and idempotent, but annotations already do.

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 100% for the single enum parameter 'tipo', which is well-documented with each option explained. The description does not add any new parameter semantics beyond what the schema already provides.

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 clearly states the tool queries Brazilian export rules for digital services, specifying the types of returns (tax exemptions, NFS-e instructions, FX rules, crypto restrictions). It distinguishes itself from sibling tools like calculate_fator_r and fetch_oracle_data by focusing on tax and regulatory compliance for foreign income.

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?

The description provides an explicit use case: when a Brazilian company needs to understand how to tax revenues from foreign clients/agents. It does not mention when not to use it or alternatives, but the sibling tools are distinct enough to avoid confusion.

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