send_sms

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

With no annotations, the description carries the full burden. It discloses credit spending, required confirmation, optional scheduling, and default sender ID. It doesn't cover error handling or return values, but provides solid behavioral context for a sending tool.

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 efficiently structured: one sentence of purpose, one usage warning, then bullet-like args. Every sentence adds value, no redundancy, and key details are front-loaded.

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?

Given 4 params (one optional) and an output schema (not shown), the description covers all needed context: credit spending, sender selection, scheduling options, and parameter formatting. It's complete for effective use without further aid.

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 0%, so the description wholly defines parameters: 'to' format (E.164), 'message' max length (1600), 'sender_id' constraints (1-11 alphanumeric) with guidance, and 'schedule_at' format (ISO-8601 UTC). This adds significant meaning beyond the schema's bare types/titles.

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 'Send a single SMS message, optionally scheduled for future delivery,' with a specific verb and resource. It distinguishes from siblings like 'send_bulk_sms' (multiple) and 'get_message' (retrieval), making the tool's 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?

It warns to confirm with the user and mentions credit consumption, plus directs to 'list_sms_sender_ids' for approved sender IDs. It lacks explicit 'when not to use' or alternatives like 'send_bulk_sms', but the guidance is sufficient for typical use.

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