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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, not open-world), and the description adds the critical behavioral fact that this is guidance-only and performs no determination itself, plus what the result contains (a link and named checks). It stops short of describing any other limits, but for a link-returning guidance tool the key disclosure is present and consistent with openWorldHint=false.

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 sentences, front-loaded with the destination and the core limitation, with zero filler. Each clause earns its place by either routing or disclaiming.

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 guidance-only tool with no output schema and one optional param, the description supplies everything needed: destination, the fact that no judgment is made, and which sibling checks to combine. Nothing required to invoke it correctly is missing.

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% for the single optional 'domain' parameter, so the schema already carries its meaning. The description only alludes to it ('whether an inbox or domain is burned') without adding format or handling detail; baseline 3 applies.

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?

States a specific action (directs the person to the external Burned Inbox Checker) and explicitly disclaims what it does not do ('Does not itself determine whether an inbox or domain is burned'). It also names the sibling tools that answer parts of the question, so an agent can distinguish it from the analyze_/check_ tools without opening a schema.

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?

Gives explicit routing: use this for the external Burned Inbox Checker link, and names check_domain_reputation and check_deliverability as the in-product tools that answer part of the question. Both the when-to-use and the alternative are stated.

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