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

Beyond annotations (destructiveHint=true, idempotentHint=false), the description discloses the hold delay ('held for a few minutes first, like a new send') and the cancellation path via Relaticle notifications or Outbox, which an agent could not infer from structured fields. It does not explain why the operation is flagged destructive (e.g. whether the original failed email record is consumed), leaving one meaningful behavioral 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, front-loaded with the action, then the behavioral caveat, then the eligibility constraint. Every sentence contributes a distinct fact with no filler.

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?

An output schema exists so return values need no explanation, and the description covers the precondition, the delay window, and the cancellation route. It stops short of clarifying the state of the original failed email after retry, which matters given the destructive flag.

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 single `id` parameter is documented in the schema as the ID returned by the send tools or list emails tool. The description adds no additional meaning beyond the schema, so the 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 verb and resource ('Queue ... failed emails again') with explicit scope ('one of the current user's') and precondition ('status is failed'). An agent can distinguish this from send-email-tool, cancel-email-tool, and reschedule-email-tool 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 a clear eligibility gate ('Only an email whose status is failed can be retried') and notes the user can cancel afterwards, which implies the relationship to cancel-email-tool. It does not explicitly name an alternative tool or state when to prefer reschedule-email-tool instead, so sibling routing is implied rather than spelled out.

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