SvelteLS.MCP

Instructions

Implementation Reference

• src/tools/diagnostics.ts:38-91 (handler)

  The async handler function that implements the logic for 'get_diagnostics' tool.

    async ({ filePath, minSeverity, waitMs }): Promise<ToolResult> => {
      try {
        const prep = await prepareDocumentRequest(lsp, filePath);
        if ("error" in prep) return textResult(prep.error);
  
        const diagnostics = await lsp.waitForDiagnostics(
          prep.uri,
          waitMs ?? 5000
        );
  
        if (!diagnostics || diagnostics.length === 0) {
          return textResult(
            `No diagnostics found in ${basename(filePath)}.`
          );
        }
  
        const minSev = parseSeverity(minSeverity);
        const lines: string[] = [];
        let count = 0;
  
        for (const diag of diagnostics) {
          const severity = diag.severity ?? 4;
          if (severity > minSev) continue;
  
          const sevLabel = severityLabel(severity);
          const line = (diag.range?.start?.line ?? 0) + 1;
          const code =
            typeof diag.code === "object"
              ? (diag.code as any)?.value?.toString() ?? ""
              : diag.code?.toString() ?? "";
          const message = diag.message ?? "";
  
          let entry = `  [${sevLabel}] ${basename(filePath)}:${line}`;
          if (code) entry += ` ${code}`;
          entry += `: ${message}`;
          lines.push(entry);
          count++;
        }
  
        if (count === 0) {
          return textResult(
            `No diagnostics at severity '${minSeverity ?? "warning"}' or above in ${basename(filePath)}.`
          );
        }
  
        return textResult(
          `Found ${count} diagnostic(s) in ${basename(filePath)}:\n\n` +
            lines.join("\n")
        );
      } catch (ex) {
        return textResult(formatError(ex));
      }
    }
  );

• src/tools/diagnostics.ts:16-91 (registration)

  Registration of the 'get_diagnostics' tool in the MCP server.

  server.registerTool(
    "get_diagnostics",
    {
      title: "Get Diagnostics",
      description:
        "Get compiler errors, warnings, and diagnostics for a file. Opens the document to trigger computation if needed.",
      inputSchema: z.object({
        filePath: z.string().describe("Absolute path to the file"),
        minSeverity: z
          .string()
          .optional()
          .describe(
            "Minimum severity to include: error, warning, info, hint. Default: warning"
          ),
        waitMs: z
          .number()
          .optional()
          .describe(
            "How long to wait for diagnostics (ms). Default: 5000. Increase for large files."
          ),
      }),
    },
    async ({ filePath, minSeverity, waitMs }): Promise<ToolResult> => {
      try {
        const prep = await prepareDocumentRequest(lsp, filePath);
        if ("error" in prep) return textResult(prep.error);
  
        const diagnostics = await lsp.waitForDiagnostics(
          prep.uri,
          waitMs ?? 5000
        );
  
        if (!diagnostics || diagnostics.length === 0) {
          return textResult(
            `No diagnostics found in ${basename(filePath)}.`
          );
        }
  
        const minSev = parseSeverity(minSeverity);
        const lines: string[] = [];
        let count = 0;
  
        for (const diag of diagnostics) {
          const severity = diag.severity ?? 4;
          if (severity > minSev) continue;
  
          const sevLabel = severityLabel(severity);
          const line = (diag.range?.start?.line ?? 0) + 1;
          const code =
            typeof diag.code === "object"
              ? (diag.code as any)?.value?.toString() ?? ""
              : diag.code?.toString() ?? "";
          const message = diag.message ?? "";
  
          let entry = `  [${sevLabel}] ${basename(filePath)}:${line}`;
          if (code) entry += ` ${code}`;
          entry += `: ${message}`;
          lines.push(entry);
          count++;
        }
  
        if (count === 0) {
          return textResult(
            `No diagnostics at severity '${minSeverity ?? "warning"}' or above in ${basename(filePath)}.`
          );
        }
  
        return textResult(
          `Found ${count} diagnostic(s) in ${basename(filePath)}:\n\n` +
            lines.join("\n")
        );
      } catch (ex) {
        return textResult(formatError(ex));
      }
    }
  );