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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safety profile is covered; the description still adds real value by disclosing the returned fields (revision, checkedAtMs, pendingUntilMs) and the semantic caveat that absent measurement is not zero engagement. The pendingUntilMs/revision detail hints at async settling behavior that annotations do not convey.

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?

Purpose is front-loaded in the first sentence, followed by input, return shape, safety reassurance, a semantic caveat, and a resource pointer. Every sentence is short and load-bearing; nothing is redundant.

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 usefully enumerates the returned fields, and it covers read-only semantics plus a guide resource for follow-up. The only gap is deeper payload parameter guidance (revision/cursor/reviewHash) for what is a fairly complex nested input.

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 50% and the payload is an opaque nested object, but the description compensates partially by naming 'domainId' as the required input, which the schema does not document. It says nothing about expectedRevision, cursor, or reviewHash mentioned generically in the payload description, so the compensation is incomplete.

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?

Specific verb plus tightly scoped resource: reading provider click/open measurement settings for an owned sending domain. The phrase 'actual provider ... settings' clearly separates it from configuration-type siblings in the email family, though no sibling is named explicitly.

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?

'This does not change settings' implies the read-only counterpart to configure_email_tracking, and 'Missing measurement is not zero engagement' is useful interpretive guidance. However, no alternative tool is named and no explicit when/when-not condition is given, so routing must be inferred.

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