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

Annotations already declare readOnly, idempotent, non-destructive. The description adds behavior beyond them: that no automatic polling happens and that the caller must space out repeat calls, which is the key operational trait for an async-result endpoint. It doesn't say what a pending vs completed result looks like, leaving a gap.

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?

Three short sentences, zero filler, with the scope limitation and the polling constraint front-loaded. Every sentence 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?

There is no output schema, so the description should carry return-value semantics; saying it returns 'status and result' is too thin for a polling endpoint. An agent doesn't learn which status values indicate completion or how to distinguish pending from failed, which is the main thing this tool is for.

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 0% and the single parameter verification_id is undocumented in both schema and description. The description never says where the ID comes from (presumably the return of mailercheck_verify_email) or what form it takes, so it fails to compensate for the coverage gap.

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 verb and resource ('Read the status and result of a previously submitted asynchronous email check') and explicitly negates the adjacent write path ('Does not start new verification'), which cleanly separates it from the mailercheck_verify_email sibling.

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 clear invocation guidance: use this only for an already-submitted check, call once and wait before polling again. It stops short of naming mailercheck_verify_email as the tool that initiates checks, so the routing is implied rather than explicit.

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