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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds valuable behavioral context beyond those annotations: output is self-contained, printable, consistent in layout across syntaxes, and localized via language labels. No contradictions with annotations are 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, well-structured sentence that front-loads the core purpose and packs in the most relevant behavioral details without waste. Every clause earns its place.

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 presence of a complete input schema, an output schema, and safety annotations, the description covers the key behavioral aspects an agent needs: output type, self-contained nature, printability, layout consistency, and localization. It could slightly expand on when to prefer this over sibling tools, but nothing critical is missing for correct invocation.

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%, and the schema already explains lang, path, and file_base64 in detail. The description adds little parameter-specific meaning beyond reinforcing that language affects rendering labels, which the schema already states. Baseline 3 is appropriate.

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 states a specific verb ('renders') and resource ('invoice') with a clear output form: human-readable, self-contained, printable HTML. This clearly distinguishes it from siblings like invoice_to_csv, invoice_to_datev, read_invoice, and validate_invoice, which produce different output types or serve different objectives.

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 when to use this tool: when a human-readable, self-contained HTML representation of an invoice is needed, regardless of source syntax. It does not explicitly name alternatives or state when not to use it, but the render-to-HTML framing provides clear contextual guidance compared to the sibling tools.

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