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

Beyond the annotations (readOnlyHint=false, openWorldHint=true, destructiveHint=false), the description discloses the state transition (unsent estimate becomes Pending, approval moves it to Approved), the per-call confirmation default with an opt-out, that the action reaches other people and should be user-confirmed, and the API key requirement. This is unusually rich behavioral context.

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 opening two sentences are largely redundant, both restating 'email or text with an approval link'. The content is front-loaded but the duplication costs 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 2-param mutation with no output schema, the description covers purpose, state effects, confirmation policy, and auth requirements. It does not describe the response, but no output schema exists to make that mandatory.

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 schema already documents both parameters including the enum and the default. The description restates email/text/both but adds no syntax or format detail beyond the schema, so baseline 3 is correct.

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 states a specific verb (send/email/text) and resource (estimate) with scope: delivering a client-facing estimate with an approval link. An agent can distinguish this from sibling read/create tools like list_estimates or create_estimate immediately.

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 clear context for use (deliver an already-created estimate to the client) and an explicit default behavior for confirmation, plus the ability to disable it. It does not explicitly name alternatives or prerequisites like 'estimate must exist first', so it stops short of a 5.

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