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

The description adds the behavioral trait of automatic CBS/IBS calculation, which is beyond the basic destructiveHint annotation. However, it does not disclose other side effects (e.g., whether the invoice is registered with the government, generates a protocol, or is irreversible beyond the annotation's implication). The annotation covers the destructive nature, so the description provides some extra context but not rich behavioral detail.

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 sentence that front-loads the core action and includes the key differentiator (CBS/IBS calculation). It is concise with no filler or redundancy.

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 mutating financial tool with no output schema, the description is relatively brief. It covers the main purpose and a key feature, but does not explain return values, asynchronous behavior, or prerequisites beyond the required inputs. Given the complexity and lack of output schema, a bit more context would be beneficial, but the description is not misleading and covers the essential action.

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 input schema has 100% description coverage, so the schema already documents each parameter thoroughly. The description merely mentions that tomador and serviço are required, but adds no additional meaning beyond what the schema provides. This matches the baseline for high schema coverage.

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's function with a specific verb ('Emite' - issues) and resource (Nota Fiscal de Serviço Eletrônica NFS-e). It also distinguishes itself from siblings like cancelar_nfse by specifying the emission action and automatic CBS/IBS calculation.

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 implies the primary use case (emitting an NFS-e) and states required inputs (tomador and serviço), providing context for when to use it. It does not explicitly list alternatives or exclusions, but the sibling context makes the differentiation clear.

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