> ## Documentation Index > Fetch the complete documentation index at: https://docs.athenahq.ai/llms.txt > Use this file to discover all available pages before exploring further. # Update Brand Fact > Updates one brand fact's text, source URL, or confidence. Only provided fields change; pass source_url: "" to clear the stored source. Editing text re-embeds the fact for semantic search; a 409 is returned when the new text collides with a sibling fact captured from the same AI response (duplicates across other facts are not rejected here and are left to Knowledge Base dedup). Review status never changes through this endpoint. Requires a website-admin API key. Also available as the MCP tool `update_brand_fact`. ## OpenAPI ````yaml /api-reference/openapi.json patch /api/v1/knowledge-base/facts/{fact_id} openapi: 3.1.0 info: title: AthenaHQ API description: >- AthenaHQ API provides programmatic access to manage your websites and prompts for AI-powered content optimization. version: 1.0.0 contact: email: support@athenahq.ai servers: - url: https://api.athenahq.ai description: Production server security: - apiKey: [] tags: - name: Basics description: Core API operations for managing websites and prompts - name: Metrics description: Metrics and analytics endpoints for tracking AI visibility - name: Billing description: Billing and credits endpoints for managing usage - name: Team Management description: Endpoints for managing team members and invitations - name: Groups description: Endpoints for managing groups of websites - name: Content description: >- Endpoints for accessing Content Hub data — tabs, tracked URLs, and per-URL prompt breakdowns. - name: Pitch Workspace description: >- Endpoints for accessing pitch workspace reports — org-scoped pitch runs with competitors, prompts, attributes, and aggregate metrics. - name: Knowledge Base description: >- Endpoints for reading the brand Knowledge Base — approved brand facts and the pillars that organize them. paths: /api/v1/knowledge-base/facts/{fact_id}: patch: tags: - Knowledge Base summary: Update Brand Fact description: >- Updates one brand fact's text, source URL, or confidence. Only provided fields change; pass source_url: "" to clear the stored source. Editing text re-embeds the fact for semantic search; a 409 is returned when the new text collides with a sibling fact captured from the same AI response (duplicates across other facts are not rejected here and are left to Knowledge Base dedup). Review status never changes through this endpoint. Requires a website-admin API key. Also available as the MCP tool `update_brand_fact`. operationId: updateBrandFact parameters: - name: fact_id in: path required: true schema: type: string format: uuid description: The fact to update. requestBody: required: true content: application/json: schema: type: object properties: website_id: type: string format: uuid description: The website the fact belongs to. text: type: string minLength: 1 maxLength: 10000 description: >- New fact statement. Caps at 10000 characters, matching the in-app edit dialog (add_brand_facts caps new facts at 2000). source_url: type: string maxLength: 2048 description: >- New source URL. An empty string clears the stored source URL. confidence: type: string enum: - high - medium - low description: New confidence level. required: - website_id responses: '200': description: The updated fact plus a pre-update snapshot of the editable fields content: application/json: schema: type: object properties: fact: $ref: '#/components/schemas/BrandFact' before: type: object description: Values of the editable fields before this update. properties: text: type: string source_url: type: - string - 'null' confidence: type: - string - 'null' enum: - high - medium - low - null required: - text - source_url - confidence required: - fact - before '400': description: Bad request - Invalid parameters content: application/json: schema: $ref: '#/components/schemas/Error' examples: missing_website_id: value: error: website_id is required blank_text: value: error: text must not be blank unsafe_source_url: value: error: source_url is not a valid URL '401': description: Unauthorized - Invalid or missing API key content: application/json: schema: $ref: '#/components/schemas/Error' '403': description: >- Forbidden - No admin access to this website, or the Knowledge Base is not enabled for the organization content: application/json: schema: $ref: '#/components/schemas/Error' examples: unauthorized_website: value: error: Unauthorized access to this website kb_not_enabled: value: error: Knowledge Base is not enabled for this organization '404': description: Not found - No fact with this id on the website content: application/json: schema: $ref: '#/components/schemas/Error' examples: fact_not_found: value: error: Fact not found '409': description: >- Conflict - The new text matches a sibling fact captured from the same AI response content: application/json: schema: $ref: '#/components/schemas/Error' examples: identical_fact: value: error: An identical fact already exists security: - apiKey: [] components: schemas: BrandFact: type: object properties: id: type: string format: uuid text: type: string description: The fact statement. status: type: string enum: - approved - pending - rejected description: Review status of the fact. confidence: type: - string - 'null' enum: - high - medium - low - null description: Confidence level assigned during ingestion, or null when unrated. source_url: type: - string - 'null' description: URL the fact was extracted from, stored without protocol. source_quote: type: - string - 'null' description: Verbatim quote from the source backing the fact. source_type: type: string enum: - research - response - upload - content_hub description: How the fact entered the Knowledge Base. pillar: $ref: '#/components/schemas/BrandFactPillar' created_at: type: string description: ISO 8601 timestamp of when the fact was added. required: - id - text - status - confidence - source_url - source_quote - source_type - pillar - created_at Error: type: object description: Error response object required: - error properties: error: type: string description: Error message describing what went wrong example: Unauthorized BrandFactPillar: type: - object - 'null' description: >- The published pillar the fact is filed under, or null when the fact is unfiled. properties: id: type: string format: uuid name: type: string required: - id - name securitySchemes: apiKey: type: apiKey in: header name: x-api-key description: >- API key for authentication. You can create one [here](https://app.athenahq.ai/organization?tab=api). ````