Confirm the InfluxDB 3 Core instance is running and listening on its default port 8181 (not 8086 — that is the v1/v2 default)
POST http://<host>:8181/api/v3/write?db=<database> with the Authorization header set to Bearer <token> and Content-Type text/plain
Send line protocol in the request body: measurement,tag_key=tag_val field_key=field_val timestamp_ns
Check for HTTP 204 No Content on success; non-2xx responses contain an error JSON body with a message field
Query data with POST http://<host>:8181/api/v3/query?db=<database> using SQL or InfluxQL in the request body and Accept: application/json
For Flight SQL / Arrow clients use gRPC on port 8181 as well — both REST and Arrow Flight share the same port in v3 Core
Known gotchas
InfluxDB 3 Core defaults to port 8181 for all HTTP API traffic — port 8086 is the default for InfluxDB v1 and v2 and will be refused on a v3 Core instance unless explicitly reconfigured
The write endpoint path is /api/v3/write — the v1 compatibility path /write and v2 path /api/v2/write may not be available on all v3 Core deployments
InfluxDB 3 Core does not support the InfluxDB v2 Tasks or Checks APIs; scheduled downsampling must be handled externally
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp