Start the application's email again

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

Goes well beyond the annotations: it discloses a specific failure mode with its HTTP status code (409 paused_for_deliverability), explains that such a pause cannot be lifted by this tool and why, and states the authentication requirement ('Needs the account token'). Annotations only cover destructiveHint=false and openWorldHint=false, so this added error and auth context is genuinely valuable.

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 action and its prerequisite in the first clause, then spends the remaining sentences on the one non-obvious edge case and the workaround to avoid. No filler or restatement of the title.

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 zero-parameter, non-destructive state-change tool with no output schema, the description covers everything an agent needs: preconditions, the blocked-case behavior, remediation guidance, and auth. Nothing is left to inference.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The only implicit input requirement is the account token, which is mentioned but not framed as a parameter.

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 ('Start this application's email again') and explicitly anchors it to the sibling that precedes it, `email_pause`. An agent can distinguish resume from pause, remove, create, and deliverability tools without opening any 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 the triggering condition (after `email_pause`), an explicit exclusion with the exact error signal (409 paused_for_deliverability), the correct alternative behavior (tell the user, who replies to the notice they were emailed), and a named anti-pattern to avoid (removing and re-adding email). This is the full when/when-not/alternative triad.

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