Send and receive iMessage, SMS, and RCS from application code via the Sendblue HTTP API — text, media, group messages, send styles, reactions, typing indicators, status callbacks, and inbound webhooks.
SkillScore100Maintained
Automatic
◆Coding pack
Last verified 8/28/2026
What it changes
Passed 24 of 24 test cases with the skill, and 12 of 24 without it.
Without skill50%
With skill100%
Checks it passed that the model alone missed
Includes from_number in the request payload
Uses POST /api/mark-read to send a read receipt
Uses GET /api/v2/messages to fetch message history
and 12 more in the full report
12 fixed12 passed either way0 still failing0 broke
Pass-rate lift
+50 pp
Tokens
+100%
Agent turns
0%
Response time
-39%
Model gemini-3.6-flashMeasured 8/28/2026v124 of 24 cases passed with skill
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 12 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 12
Prompt
Before attempting to send iMessage screen effects or tapback reactions to a customer, my service needs to determine whether their mobile number supports iMessage. Which Sendblue API endpoint performs this check?
What was checked, without and with the skill
Checked
Without skill
With skill
Uses the GET /api/evaluate-service endpoint to check iMessage availability
Missed
Passed
case-08 · gemini-3.6-flash · 8/28/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md182 linessingle file
Sendblue API
Overview
Sendblue is a REST API that sends iMessage (blue bubbles), SMS, and RCS from a provisioned phone number. Everything is plain JSON over HTTPS — no SDK is required. The API covers outbound 1:1 and group sends, iMessage effects, reactions, typing indicators, status callbacks, and inbound webhooks.
When to Use This Skill
Use when writing application code (server, worker, function) that sends Sendblue messages as part of a long-running service.
Use when receiving inbound messages via webhooks.
Use when you need features the CLI does not expose: send styles, reactions, group messages, typing indicators, status callbacks, media uploads, or the contacts API beyond basic CRUD.
Reach for [[sendblue-cli]] instead for shell-context outbound: one-shot scripts, cron jobs, agent hooks, "ping me when X" workflows.