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

The description claims idempotency and the schema's idempotency_key says retries are not re-executed/re-charged, while the annotation idempotentHint=false indicates the operation is not idempotent; this is a direct contradiction. The useful fallback and honest-failure details cannot overcome that conflict.

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 tool description is structured with example, when-to-use, cost, latency, and execution sections; the key routing guidance is front-loaded. It is slightly repetitive about not using marketing, but no major wasted content.

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?

It covers channel fallback behavior, honest failure, idempotency semantics, cost, latency, and how to retrieve the result via get_outcome. It is reasonably complete for a side-effectful send tool, though the invalid example and the idempotency contradiction leave some ambiguity.

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 only 40%, so the description needed to clarify the parameters, but its example uses recipient.id_type/id_value while the schema requires recipient.phone_or_email. It also uses business_name in the example while the schema's data description says smb_name for booking_confirmation, creating ambiguous guidance for constructing the payload.

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 names a specific resource (transactional confirmations) and enumerates concrete types: OTPs, booking confirmations, payment receipts, cancellation notices. It clearly separates this tool from conversational messaging, and the example query reinforces the intended use.

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?

Explicit WHEN TO USE and WHEN NOT TO USE sections state that this tool is for messages that must be delivered reliably and must not be used for marketing or conversational messages. Sibling differentiation is implied through the exclusions and transaction-specific examples.

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