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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false. The description adds meaningful behavioral context beyond those: prepaid per-query cost, no platform credentials needed, official-source nature, and LGPD controller responsibility. This is valuable additional disclosure.

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 concise and front-loaded with the core purpose, followed by payment, access, and legal context. Every sentence adds relevant information without filler or repetition.

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 simple one-parameter read-only query tool, the description covers the source, access model, cost, and data classification. However, it omits the expected format of 'chave' and any indication of response contents, which is more impactful given there is no output schema.

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 has one required string parameter 'chave' with 0% description coverage. The description never explains what 'chave' is, its expected format, or how to obtain it. Since schema coverage is low, the description should compensate, but it does not.

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 'SEFAZ CE: Cupom Fiscal Eletrônico (SAT), consulta em fonte oficial', giving a specific verb (consulta) and resource (CF-e from SEFAZ CE). This clearly distinguishes it from the generic sibling tools like authenticate, marketplace, and show_version.

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 useful context: it queries an official Brazilian source, requires no platform credentials, uses prepaid credit, and deals with non-confidential data. It does not explicitly state when to use it versus alternatives, but no similar sibling exists, so the context is sufficient.

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