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

With no annotations provided, the description carries the full burden and does it thoroughly. It discloses content-only analysis ("no inbox-placement guarantee"), pay-per-call pricing, the payment-signature header requirement, and the error behavior that carries payment terms. This is rich behavioral context beyond the schema.

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 front-loaded with the core function and outputs, then covers usage, exclusions, limitations, and payment behavior. Every sentence adds necessary information; none is filler or redundant with the schema.

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, outputs, when to use, when not to use, limitations, and payment requirements. With only two parameters and no output schema, an agent has everything needed to select and invoke the tool correctly. The payment-signature requirement is especially important because it affects successful 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%, so the schema already documents both query and context parameters. The description adds no new parameter-level semantics beyond the schema, though it does reinforce that analysis is content-only. Baseline 3 is appropriate when schema does the heavy lifting.

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 uses a specific verb and resource: "Full deliverability audit of email copy," and enumerates concrete outputs (0-100 score, flagged phrases with reasons, subject-line risk, rewrites, SPF/DKIM/DMARC reminders). It explicitly distinguishes itself from the sibling check-email-deliverability by contrasting a full audit with a quick pass/fail.

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?

It gives explicit when-to-use guidance: "Use when a draft failed or warned in check-email-deliverability, or before an important send." It also names the alternative clearly: "For a quick pass/fail on many emails, use check-email-deliverability." No ambiguity remains about tool selection.

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