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

Goes well beyond the annotations: describes the returned single-use email address with a 60-minute validity, the returned testId, the additive non-idempotent behavior (fresh session, prior sessions untouched), and that no auth is required. It reinforces idempotentHint=false without merely restating it, and adds lifecycle details absent from structured fields.

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?

Front-loads the core purpose and return values, then covers behavior, parameter meaning, use case, and next step in a compact sequence. Every sentence adds information an agent needs; nothing is padding.

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 supplies the critical return contract: a unique single-use test address valid for 60 minutes and a testId for later retrieval. It also gives the follow-up call, auth expectation, and non-destructive mutation behavior, which is complete for a one-parameter session-creation 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% and the enum/default are already documented in the schema. The description adds a little meaning by saying `language` controls result text, but largely repeats the schema's enum and default rather than compensating for any 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: creates a new IntoDNS.ai inbound email-test session. It explicitly distinguishes the creation step from the sibling tools get_email_test and poll_email_test by naming the returned testId as the key they consume.

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?

Clearly says when to use it: debug an outbound message's SPF/DKIM/DMARC, headers, and spam triggers, and then call poll_email_test after sending. It names the follow-up path but does not explicitly contrast create_email_test with get_email_test or state when not to use it.

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