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SMS and WhatsApp Messaging

by dev.hatchloop
OverviewDiscussionsAdmin

send_message

Destructive

Send a message on behalf of an agent's user or an SMB across WhatsApp (free during launch), SMS, email, or voice. Sends immediately; no scheduling. Five message types: transactional, reminder, follow_up, notification, marketing. Every send routes through a non-bypassable compliance gate (TCPA, GDPR, CASL, PDPL across 26 jurisdictions) that enforces opt-in consent for marketing/promotional content — marketing without recorded consent is rejected… [from $0.02/call, variable] [async→get_outcome]

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
contentYes
recipientYes
business_idNoStable id for the recipient business; used for global demand shaping.
message_typeYesIntent tag for the message. Five permitted types. 'marketing' is allowed only…
on_behalf_ofNoWho this message is FOR (your end-user's name/label). On WhatsApp this opens a…
idempotency_keyNoRetry key: a 24h replay returns the original receipt, not re-run or charged.
preferred_channelNoauto

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed3 schema fields changed
    • changedInput schema / properties / business_id / description
      Previous value: -"Optional stable id for the recipient business. Enables global demand shaping…"New value: +"Stable id for the recipient business; used for global demand shaping."
    • changedInput schema / properties / idempotency_key / description
      Previous value: -"Optional client-supplied key for safe retries. Replaying the same key within 24h returns the original receipt - the operation is NOT re-executed and NOT re-charged."New value: +"Retry key: a 24h replay returns the original receipt, not re-run or charged."
    • removedInput schema / properties / send_at_iso
      Removed value: -{
-  "description": "NOT SUPPORTED YET. We do not schedule messages. Supplying a time more than 2…",
-  "format": "date-time",
-  "type": "string"
-}
  2. Changed4 schema fields changed
    • changedInput schema / properties / business_id / description
      Previous value: -"Optional stable id for the recipient business. Enables global demand shaping (we rate-limit total inbound across ALL agents so businesses stay responsive instead of blocking us)."New value: +"Optional stable id for the recipient business. Enables global demand shaping…"
    • changedInput schema / properties / message_type / description
      Previous value: -"Intent tag for the message. Five permitted types. 'marketing' is allowed only when paired with a valid consent_record_id; the compliance gate verifies the consent at send time and rejects (compliance_violation receipt) if it's missing, expired, or revoked."New value: +"Intent tag for the message. Five permitted types. 'marketing' is allowed only…"
    • changedInput schema / properties / on_behalf_of / description
      Previous value: -"Who this message is FOR (your end-user's name/label). On WhatsApp this opens a tracked conversation and travels in-message as '#4821 for Sara (via HatchLoop)', so the business knows who it is talking to and their reply is matched back to this exact request instead of guessed. Strongly recommended for two-way channels."New value: +"Who this message is FOR (your end-user's name/label). On WhatsApp this opens a…"
    • changedInput schema / properties / send_at_iso / description
      Previous value: -"NOT SUPPORTED YET. We do not schedule messages. Supplying a time more than 2 minutes in the future is REFUSED (reason_code scheduling_not_supported) rather than sent immediately, which is what used to happen. Call send_message at the moment you want delivery, or omit this field."New value: +"NOT SUPPORTED YET. We do not schedule messages. Supplying a time more than 2…"
  3. First observed

TDQS

A3.9/5.0
Behavior5/5

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

The description adds significant behavioral context beyond the annotations: immediate send, no scheduling, non-bypassable compliance gate with consent enforcement, rejection of marketing without consent, async flow via get_outcome, and variable pricing. These are all beyond the readOnlyHint/destructiveHint flags and are crucial for correct usage.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is moderately long but each sentence contributes value: channels, immediate send, message types, compliance, pricing, and async handling. It is front-loaded with the core action, though the trailing brackets with pricing and async hint could be integrated more cleanly. Overall, it is efficient for the information conveyed.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity (7 params, nested objects, async behavior, no output schema), the description covers essential operational details: channels, message types, compliance, async outcome, and pricing. It does not describe the return value, but the reference to get_outcome provides a path. The description is sufficiently complete for an agent to understand the tool's purpose and constraints.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 57%, which is moderate. The description mentions channels and message types that map to the preferred_channel and message_type enums, but does not add detailed meaning for recipient, content, business_id, or idempotency_key. The description adds some context (e.g., on behalf of user) but not enough to compensate for the missing 43% of parameter descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's function: sending messages on behalf of an agent's user or SMB across multiple channels (WhatsApp, SMS, email, voice). It also lists the five message types, making the purpose specific and actionable. It does not explicitly differentiate from the sibling 'send_transactional_confirmation', but the general scope is clear.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description mentions 'Sends immediately; no scheduling', which implies a constraint but does not explicitly state when to use this tool versus alternatives. There is no mention of when to prefer send_transactional_confirmation or check_compliance, leaving the decision to the agent. The compliance gate is noted, but not framed as a selection criterion.

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

All SMS and WhatsApp Messaging toolsInspect
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