send_bulk_sms

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

Discloses asynchronous processing with immediate job_id return, and credit spending. No annotations provided, so description handles transparency well but could mention error handling or rate limits for completeness.

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?

Concise yet comprehensive: three sections (action, async note, warning) followed by clean parameter list. No redundant sentences, all details earned.

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?

Complete for a complex tool: covers async behavior, credit cost, confirmation requirement, parameter constraints, and references sibling tools for tracking and sender ID lookup. Output schema exists so return details are not needed.

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?

Despite 0% schema coverage, description fully compensates by detailing each parameter: recipients (E.164, 1-10k), message (max 1600 chars), sender_id (1-11 alphanumeric, with tool reference and default), name (optional campaign name). Adds constraints, types, and examples beyond 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?

Clear verb 'send', resource 'SMS', and scope 'up to 10,000 recipients' directly stated. Distinguishes from send_sms by specifying bulk and async processing.

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?

Explicitly advises confirming recipient list, message, and sender_id with the user first, noting credit cost. Recommends using get_bulk_sms_job for tracking and list_sms_sender_ids for sender_id lookup. Provides default fallback sender_id.

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