send_sms

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the action and endpoint but omits critical behavioral aspects: authentication requirements, costs, delivery guarantees, failure handling, or reversibility. For a mutation tool that sends a message, this is a significant gap.

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?

Two sentences with zero waste. The essential action is front-loaded, and the required/optional parameters are listed compactly. This is appropriately sized for the tool's simplicity.

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 simple send action, the description covers the core invocation details. However, with no output schema and no annotations, it lacks information on expected responses, error conditions, or side effects like billing. This is acceptable for a straightforward operation but not fully comprehensive for a mutation tool.

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%, so all parameters are already documented with descriptions. The description merely restates which parameters are required and optional, adding no extra semantic insight (e.g., constraints on 'text' length or sender format). Baseline 3 applies because the schema handles parameter documentation.

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 clearly states the action ('Send one SMS immediately') and identifies the exact resource (POST /api/v2/sms/send). It distinguishes itself from siblings like bulk_send_sms and schedule_sms by specifying 'one' and 'immediately', making the purpose unambiguous.

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 word 'immediately' implies use for instant sends, distinguishing it from scheduled or bulk operations. However, it does not explicitly mention when not to use it or point to alternatives (e.g., 'use bulk_send_sms for multiple messages'), leaving some inference to the agent.

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