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

Annotations already declare destructiveHint=true, openWorldHint=true, and idempotentHint=false, but the description adds real behavioral context: the email goes out at once, the estimate transitions to Awaiting Approval, and there is a per-call confirmation prompt that can be disabled. It notably omits the consequence of non-idempotency — that calling it twice sends two emails — which is the most important operational caveat for this tool.

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?

The core action and its immediate effect are front-loaded in the first sentence, and each subsequent sentence carries distinct information about channel, timing, state change, and confirmation. The second sentence ("Sends as the Send button of the estimate page does, by email only") is somewhat redundant with the first and slightly awkward, costing a point.

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 destructive, open-world, non-idempotent action with no output schema, the description covers the essentials an agent needs: what is sent, to whom, immediately, with a visible state change and an approval gate. The remaining gaps — duplicate-send risk on retry, failure modes, and the response payload — are meaningful but secondary.

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 100%, and every parameter (email, message, subject, option_ids, estimate_id) already documents its default and source in the schema. The description only gestures at options ("approve one of its options") without adding format, constraint, or selection semantics beyond what the schema provides, so the baseline of 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?

The description opens with a specific verb and resource ("Email an estimate to the customer") and states the outcome (a link to approve one of its options). It implicitly separates itself from the invoice-sending siblings by being estimate-specific, but it never names an alternative, so sibling differentiation is left to inference.

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?

It gives implied context ("Sends as the Send button of the estimate page does") which tells the agent this is the programmatic equivalent of the UI action, and "by email only" narrows the channel. There is no explicit when-not-to-use guidance, no mention of prerequisites such as the estimate needing to exist or be in a sendable state, and no named alternative for other delivery paths.

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