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

Goes well beyond the annotations (readOnlyHint, openWorldHint) by disclosing the pricing model ($0.002 USDC, x402, Base/Solana/Arc, failed calls free), the character limit, the placeholder behavior for unknown data, the fact that the output is a draft that must be reviewed before sending, and the tone/language/intent options. This is rich behavioral context.

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 that are front-loaded with the core purpose and constraints, followed by pricing details. Every clause earns its place; no 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?

The description covers purpose, constraints, cost, and output handling. Since an output schema exists, it does not need to explain return values. However, it could mention any rate limits or authentication requirements beyond the payment mechanism, which is already covered. It is nearly complete for a relatively simple text-generation tool.

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 coverage is 100%, so the schema already documents all five parameters. The description does add some value by restating the intent options and mentioning the 10,000-character limit for the email parameter, but the schema already provides this. 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 (drafts) and resource (a reply, subject and body) to a received e-mail. It enumerates the intent options and specifies that a placeholder system is used for unknown dates/numbers/names, which is precise and distinguishes it from siblings like text_paraphrase or translate.

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 clearly implies this is for drafting replies to received e-mails, but does not explicitly state when NOT to use it (e.g., for original e-mails use a different tool) or name any alternatives. It does tell the user to read the result before sending, which is a usage guideline.

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