send_sms

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

While the annotation destructiveHint: true already flags the side-effecting nature, the description adds a new behavioral constraint: 'Requires user confirmation before sending.' This goes beyond the annotation by specifying a mandatory approval step. It also clarifies that the tool sends only a single SMS, avoiding potential bulk-send assumptions. No contradiction with annotations.

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 description is two sentences, with the first stating the primary action and the second stating a critical prerequisite. Every word earns its place, and the key information is front-loaded. No redundancy or 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?

The tool is simple: 3 fully documented parameters, a destructive annotation, and no output schema. The description covers the core purpose and the confirmation requirement, while the schema handles parameter details. The provider is named in the first sentence. This is sufficient for correct invocation, though not all possible edge cases (e.g., account prerequisites) are addressed, so a 4 rather than 5 is given.

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?

All three parameters are fully described in the input schema (100% coverage), including recipient format, message content, and sender default. The description adds no parameter-specific information. Per the rubric, with high schema coverage, a baseline of 3 is appropriate.

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 begins with 'Send a single SMS via ThaiBulkSMS,' clearly stating the action (send), the resource (SMS), and the service provider. It distinguishes itself from sibling tools like send_email by specifying SMS, and the word 'single' defines the scope. This meets the 'specific verb+resource' benchmark.

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?

The description offers no guidance on when to use this tool versus alternatives (e.g., send_email or OTP tools). The 'Requires user confirmation before sending' note is a precondition, not usage context. No exclusions or alternative recommendations are provided, leaving the agent without decision-making support.

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