Claude Paste MCP

Instructions

Implementation Reference

• src/index.js:52-122 (handler)

  The server request handler for CallToolRequestSchema handles the 'collect_pasted_items' tool by calling the runPowerShellPopup function and formatting the result.

  server.setRequestHandler(CallToolRequestSchema, async (request) => {
    if (request.params.name !== TOOL_NAME) {
      throw new Error(`Unknown tool: ${request.params.name}`);
    }
    debugLog("=== Tool called: collect_pasted_items ===");
    try {
      const items = await runPowerShellPopup();
      debugLog(`Received ${items.length} items from popup`);
      
      // If empty array, treat as cancel
      if (!items || items.length === 0) {
        return {
          content: [
            {
              type: "text",
              text: "User cancelled the paste operation or no items were confirmed.",
            },
          ],
        };
      }
      // Group items by type
      const images = items.filter(i => i.type === "image");
      const tables = items.filter(i => i.type === "table");
      const richtext = items.filter(i => i.type === "richtext");
      const text = items.filter(i => i.type === "text");
  
      // Build friendly summary
      const parts = [];
      if (images.length > 0) {
        parts.push(`${images.length} image${images.length > 1 ? 's' : ''}`);
      }
      if (tables.length > 0) {
        parts.push(`${tables.length} table${tables.length > 1 ? 's' : ''}`);
      }
      if (richtext.length > 0) {
        parts.push(`${richtext.length} rich text item${richtext.length > 1 ? 's' : ''}`);
      }
      if (text.length > 0) {
        parts.push(`${text.length} text item${text.length > 1 ? 's' : ''}`);
      }
  
      const count = items.length;
      const itemNames = items.map(i => i.name).join(", ");
      const summaryText = `[${parts.join(', ')} attached: ${itemNames}]`;
  
      // Build machine-readable JSON block
      const jsonBlock = `ITEMS_JSON: ${JSON.stringify(items)}`;
      return {
        content: [
          {
            type: "text",
            text: summaryText,
          },
          {
            type: "text",
            text: jsonBlock,
          }
        ],
      };
    } catch (error) {
      return {
        content: [
          {
            type: "text",
            text: `Error collecting items: ${error.message}`,
          },
        ],
        isError: true,
      };
    }
  });

• src/index.js:33-51 (registration)

  The server request handler for ListToolsRequestSchema registers the 'collect_pasted_items' tool definition.

  server.setRequestHandler(ListToolsRequestSchema, async () => {
    return {
      tools: [
        {
          name: TOOL_NAME,
          description: "Opens a Windows popup to let the user paste images, Excel tables, rich text, or plain text from their clipboard. Use this when the user indicates they want to attach content (e.g. via @pic).",
          inputSchema: {
            type: "object",
            properties: {
              prompt_context: {
                type: "string",
                description: "Optional context about what the user is expected to paste."
              }
            },
          },
        },
      ],
    };
  });

• src/index.js:123-175 (helper)

  The 'runPowerShellPopup' function acts as a helper that spawns a PowerShell process to retrieve clipboard content.

  function runPowerShellPopup() {
    return new Promise((resolve, reject) => {
      const ps = spawn("powershell", [
        "-NoProfile",
        "-ExecutionPolicy", "Bypass",
        "-File", POWERSHELL_SCRIPT
      ], {
        // Ensure proper encoding
        env: { ...process.env, PYTHONIOENCODING: 'utf-8' }
      });
      let stdoutData = "";
      let stderrData = "";
      ps.stdout.on("data", (data) => {
        stdoutData += data.toString();
      });
      ps.stderr.on("data", (data) => {
        stderrData += data.toString();
      });
      ps.on("close", (code) => {
        debugLog(`Exit code: ${code}`);
        debugLog(`stdout length: ${stdoutData.length}`);
        debugLog(`stdout: ${stdoutData.substring(0, 1000)}`);
        debugLog(`stderr: ${stderrData}`);
  
        if (stderrData && code !== 0) {
          debugLog(`PS Error: ${stderrData}`);
        }
        const trimmed = stdoutData.trim();
        if (!trimmed) {
          debugLog("Empty output, resolving []");
          resolve([]);
          return;
        }
        try {
          const lines = trimmed.split('\n');
          const lastLine = lines[lines.length - 1].trim();
          debugLog(`Parsing last line: ${lastLine.substring(0, 500)}`);
          const result = JSON.parse(lastLine);
  
          if (Array.isArray(result)) {
            debugLog(`Parsed array with ${result.length} items`);
            resolve(result);
          } else {
            debugLog("Parsed single object, wrapping in array");
            resolve([result]);
          }
        } catch (e) {
          debugLog(`Parse error: ${e.message}`);
          debugLog(`Raw output: ${trimmed}`);
          resolve([]);
        }
      });
    });