FsMcp/.github/prompts/create-mcp-tool-from-openapi.prompt.md

Reusable Prompt: Add a new MCP tool from fsopenapi.json

Use this prompt when adding a new MCP tool to this project.

---

You are working in the fsmcp workspace.

Goal

Add a new MCP tool for this endpoint:

• Endpoint path: <ENDPOINT_PATH>
• HTTP method: <HTTP_METHOD>

Use fsopenapi.json as the source of truth for request/response schemas and constraints.

Required implementation rules

1. Read OpenAPI docs first

   • Find endpoint details in fsopenapi.json:
     • summary/description
     • parameters (path/query/body)
     • response schema(s)
     • relevant referenced component schemas and enums
   • Use exact API field names via JsonPropertyName.

2. Update endpoint constants

   • Add a new endpoint constant/function in FsMcp/Endpoints.cs.
   • Follow existing style (ApiBase, interpolation, naming consistency).

3. Create a new tool class

   • Create file in FsMcp/Tools/ named after the endpoint purpose, e.g. RegionStoresTools.cs.
   • Add one MCP tool method with [McpServerTool] and detailed [Description].
   • Inject and use FoodsharingApiClient.
   • Always call await _apiClient.EnsureLoginAsync(); before HTTP calls.
   • Validate input parameters where appropriate (e.g. IDs > 0).
   • Use strongly typed request/response models (record types).
   • Add rich per-field [Description] metadata on model properties.
   • Reuse existing shared models if already present (avoid duplication).

4. Register tool in host

   • Add .WithTools<YourNewToolsClass>() in FsMcp/Program.cs.

5. Extend documentation

   • Update FsMcp/README.md with a new section for the tool including:
     • tool name
     • endpoint + purpose
     • input parameters
     • auth behavior (USERNAME, PASSWORD, CSRF)
     • output shape highlights
     • enum/date/data-quality notes that help consumers

6. Validate

   • Build with:
     • dotnet build FsMcp/FsMcp.csproj -c Debug
   • If build fails due to pre-existing unrelated issues, clearly state that and confirm whether new files are clean.

Style constraints

• Keep changes minimal and focused.
• Match existing C# style and naming.
• Do not add unrelated refactors.
• Preserve API payload shape; do not rename wire-level JSON fields.

Output format expected from you

At the end, provide:

1. Short summary of what changed.
2. List of changed files.
3. Validation result.
4. Any blockers or follow-up suggestions.

Variables to fill before running this prompt

• <ENDPOINT_PATH> e.g. /api/regions/{regionId}/stores
• <HTTP_METHOD> e.g. GET

Example invocation

"Add a new MCP tool for GET /api/regions/{regionId}/stores using this reusable prompt and implement all required steps."