Send a single SMS message to a phone number in E.164 format (+212600000000).
| Name | Required | Description | Default |
|---|---|---|---|
| to | Yes | Recipient phone number in E.164 format (+212600000000) | |
| message | Yes | Text content of the SMS | |
| sender_id | No | Optional approved custom Sender ID |
Changes observed during successful MCP inspections.
Input schema / properties / sender_id / descriptionPrevious value: -"Optional Sender ID"New value: +"Optional approved custom Sender ID"Input schema / properties / to / descriptionPrevious value: -"Phone number in E.164 format (+212600000000)"New value: +"Recipient phone number in E.164 format (+212600000000)"Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of disclosing behavioral traits. It only states that an SMS is sent and includes an E.164 format note, but it does not disclose side effects such as cost/balance deduction, delivery behavior, rate limits, sender_id approval requirements, or error outcomes.
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 a single sentence with no filler or redundancy. It front-loads the core operation and includes the key formatting constraint without wasting words.
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 tool with fully described parameters, this description is minimally viable for invocation. However, without annotations or an output schema, it leaves gaps around return values, side effects, and alternatives, so it is not fully complete.
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 the parameters are already documented in the input schema. The description adds no meaningful information beyond what the schema provides; it only repeats the E.164 format for the 'to' parameter.
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 and resource: send a single SMS message to a phone number. The E.164 format is included, making the scope concrete. However, it does not explicitly differentiate from sibling tools like send_otp or send_bulk_sms beyond the word 'single'.
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 'single' implies this tool is for one-off SMS sending rather than bulk messaging, but there is no explicit guidance about when to use send_sms versus send_bulk_sms or send_otp. The usage context is only implied, not stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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