openapi-spec-validator

id	openapi-spec-validator
name	OpenAPI Spec Validator
version	1.0.0
description	Validates an OpenAPI 3.x or Swagger 2.0 specification file (YAML or JSON) against the official schema, returning a list of validation errors with path, message, and severity. Checks for missing required fields, invalid $ref references, malformed response schemas, and security scheme misconfigurations. Returns valid=true when the spec has zero errors.
capability	{"type":"code-execution","inputs":["spec_path:string","strict:boolean"],"outputs":["errors:list","warnings:list","error_count:int","valid:boolean"]}
graph	{"depends_on":[],"complements":["api-mock-generator","sdk-code-generator"],"co_used_with":["postman-collection-exporter","api-doc-publisher"]}
compatibility	{"claude_code":true,"gemini":true,"codex":true,"cursor":true,"mcp":true}
risk	safe

What this skill does

Parses an OpenAPI 3.x or Swagger 2.0 spec file and runs full schema validation using the official OpenAPI JSON Schema. Returns every error with the JSON path where it occurred, a human-readable message, and the severity level. In strict mode, also validates that all $ref references resolve and that every endpoint has at least one documented response.

Inputs

• spec_path — path to the .yaml, .yml, or .json spec file
• strict — when true, enables additional checks: unresolved $ref, undocumented endpoints, missing example values (default: false)

Outputs

• errors — list of {path, message, severity} objects for spec violations (severity: error)
• warnings — list of {path, message, severity} objects for best-practice issues (severity: warning)
• error_count — number of error-severity violations
• valid — true when error_count == 0

Common errors caught

Error	Example path
Missing required field	#/paths/~1users/get/responses
Invalid $ref	#/components/schemas/User/properties/id
Wrong type for parameter	#/paths/~1items/get/parameters/0/schema
Security scheme not defined	#/paths/~1admin/get/security/0
Response schema missing type	#/paths/~1users/post/responses/200/content

Example

# validate a spec file
asf query "validate my openapi spec at ./api/openapi.yaml"

{
  "errors": [
    {
      "path": "#/paths/~1users/get/responses",
      "message": "Required property 'responses' is missing",
      "severity": "error"
    }
  ],
  "warnings": [],
  "error_count": 1,
  "valid": false
}

Notes

• Supports OpenAPI 3.0.x, 3.1.x, and Swagger 2.0
• Use strict: true in CI pipelines to enforce documentation completeness
• YAML and JSON formats both supported; auto-detected from file extension