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

Annotations cover the safety profile (readOnly=false, destructive=false, openWorld=true), and the description adds meaningful context beyond them: the recipient is external, the customer can pay in full or in part via a link, template selection differs by channel, and a Cotlet API key with app access is required. Return/response behavior is not described, but no output schema exists to lean on, keeping this at a 4.

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 core action and keeps related details (channels, templates, payment, confirmation, auth) in a compact block. The UI-referencing sentence 'Sends the invoice from the Send button of the app' is slightly wasteful but not damaging.

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 an outward-facing mutation tool with no output schema, it covers the important pieces: external reach, required confirmation, default vs. override behavior, template choice, and API key requirement. It is essentially complete for correct invocation.

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%, so the baseline is 3. The description nonetheless enriches the 'template' parameter by explaining channel-dependent template semantics ('Text an invoice template' by text, any 'Job/WO Email template' by email), adding meaning beyond the schema.

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 ('Email or text an invoice with a link to view and pay it online'), making the action and outcome unambiguous. It does not explicitly differentiate itself from sibling tools like service-fusion_send_estimate or service-fusion_create_invoice, so it stops short of a 5.

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?

Provides clear operational context: 'Reaches other people: confirm with the user before each call' and notes the default confirmation gate can be toggled off for this tool. It gives when-to-confirm guidance but does not name alternative tools or exclusions, so not a 5.

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