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

Annotations provide no behavioral hints beyond all-false flags, so the description carries the burden. It adds useful behavior: output is email-ready plain text, the .txt download link is valid for one hour, and the tool is free. It also implies a non-mutating operation by saying 'turn a credit note into a summary' rather than update or delete. It does not explicitly state that no changes are made to the credit note, but the disclosed content and link behavior are solid.

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?

Two concise sentences deliver the purpose, output contents, link validity, pricing, and an explicit alternative. Everything is front-loaded and every clause adds value; no fluff 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?

With no output schema, the description explains the return content well enough for an agent to invoke the tool and interpret the result. It also covers the temporary link and the alternative PDF tool. Minor gaps remain: it doesn't describe error behavior or explicitly confirm that the operation is read-only, but for a simple text-generation tool the coverage is strong.

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 fully describes id, greeting, and sign_off, including a concrete example for id and defaults for greeting and sign_off. The description does not need to repeat these details, and it adds little parameter-specific meaning beyond clarifying the purpose of the generated text. Baseline of 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 and resource: 'Turn a credit note into a plain-text summary to paste into an email.' It then enumerates the exact content pieces (negated line table, VAT lines, total, reason, what comes off the invoice), and it explicitly distinguishes itself from credit_note_pdf by noting that tool writes the A4 document. This removes any ambiguity about the tool's purpose.

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 makes the intended use clear: generate a plain-text summary for email, plus a temporary .txt download link. It also names the alternative credit_note_pdf for A4 documents. It does not explicitly state when not to use other credit note tools, but the email-vs-PDF contrast provides actionable guidance.

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