Visual Crossing Weather API vs Xweather Weather API

Visual Crossing Weather API

History from 1970, current conditions and a 15-day forecast from one endpoint. Key only in the query string on the REST API.

Xweather Weather API

A public OpenAPI file with 236 operations, a hosted MCP server in the official registry and a free tier of 15,000 accesses a month suit agents. REST credentials travel only in the query string, per-minute limits are unpublished, and the group terms bar commercial use of free plans and passing data to third parties unless a service description allows it.

Visual Crossing Weather API

1. Always pass include= and elements=. A bare call returns days, hours and current for every element and burns records
2. Count records before a backfill. Hourly data is 24 records a day, so a year for one place is 8,760
3. Pass unitGroup=metric. The default is US units
4. Use the MCP server with X-VC-API-Key rather than pasting the key into a URL
5. Keep to one request at a time on Free and Professional. A second concurrent job returns 429

Xweather Weather API

1. Check success and error.code on every response. Application errors such as invalid_location return HTTP 200 with success false
2. Send fields, limit and plimit. The docs put a 15-day hourly forecast at about 600 KB, and about 25 KB with three fields
3. Read X-Cost-Tokens after each call. Cost is the endpoint multiplier times the intervals requested, so narrow from and to
4. For MCP, send Authorization: Bearer <client_id>_<client_secret> and avoid the api_key query parameter, which puts the secret in the URL
5. Add include_tags or include_tools to the MCP URL to load only the tool groups the task needs
6. On 429 read Retry-After and the X-RateLimit-Reset-* headers. maxhits_min clears at the next minute, maxhits at the period reset