send_sms

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

With no annotations provided, the description carries full burden for behavioral disclosure. While it mentions the action ('Send') and return type ('SMS send response with transaction details'), it lacks critical behavioral information such as authentication requirements, rate limits, error conditions, cost implications, or delivery guarantees. The description provides basic functional information but misses important operational context.

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 perfectly structured and economical. It begins with a clear purpose statement, then provides organized parameter documentation in an Args/Returns format, with each sentence serving a specific purpose. No wasted words or redundant information.

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 that there's an output schema (which handles return values), the description covers the basic purpose and parameters well. However, for a mutation tool with no annotations, it should provide more behavioral context about authentication, costs, or operational constraints. The parameter documentation is excellent, but overall completeness is limited by the lack of behavioral transparency.

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?

With 0% schema description coverage, the description fully compensates by providing clear semantic meaning for all 3 parameters. It explains what 'to' represents (recipient mobile number with format requirement), what 'text' contains (message content with length limit), and the purpose of 'reference_id' (optional tracking). This adds significant value beyond the bare 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?

The description clearly states the specific action ('Send a single SMS message'), identifies the resource ('via Promotexter'), and distinguishes it from the only sibling tool 'get_balance' which is a read operation. The verb+resource combination is precise and 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 description implies usage context through the parameter documentation (e.g., 'must be valid mobile number format', 'maximum 1000 characters'), but doesn't explicitly state when to use this tool versus alternatives or any prerequisites. There's no explicit guidance on when-not-to-use or comparison with sibling tools.

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