Gemini CLI MCP Server

Instructions

Implementation Reference

• lib/fixed-mcp-tool.js:353-387 (handler)

  MCP CallTool handler for 'fetch-chunk': destructures args, calls getChunkedEdits helper, formats chunk response with progress info and instructions for fetching more chunks if available.

  case "fetch-chunk":
      const { cacheKey, chunkIndex: fetchChunkIndex } = args;
      console.error('[GMCPT] fetch-chunk tool called with cacheKey: ' + cacheKey + ', chunkIndex: ' + fetchChunkIndex);
      
      try {
          const chunkResult = getChunkedEdits(cacheKey, parseInt(fetchChunkIndex));
          
          // Format the chunk information
          const chunkInfo = `CHUNK ${chunkResult.chunk}/${chunkResult.totalChunks} (Cache Key: ${chunkResult.cacheKey})\n\n${chunkResult.content}`;
          
          if (chunkResult.hasMore) {
              const nextChunk = chunkResult.chunk + 1;
              const remainingChunks = chunkResult.totalChunks - chunkResult.chunk;
              return {
                  content: [{
                      type: "text",
                      text: chunkInfo + `\n\n[Use fetch-chunk tool with cacheKey "${chunkResult.cacheKey}" and chunkIndex ${nextChunk}-${chunkResult.totalChunks} to get remaining ${remainingChunks} chunks]`
                  }]
              };
          } else {
              return {
                  content: [{
                      type: "text",
                      text: chunkInfo + "\n\n[This is the final chunk]" 
                  }]
              };
          }
      } catch (error) {
          return {
              content: [{
                  type: "text",
                  text: `Error retrieving chunk: ${error.message}`
              }]
          };
      }

• lib/fixed-mcp-tool.js:180-198 (schema)

  Input schema definition for the fetch-chunk tool, specifying required cacheKey (string) and chunkIndex (number >=1).

  {
      name: "fetch-chunk",
      description: "Retrieves cached chunks from a changeMode response. Use this to get subsequent chunks after receiving a partial changeMode response.",
      inputSchema: {
          type: "object",
          properties: {
              cacheKey: {
                  type: "string",
                  description: "The cache key provided in the initial changeMode response"
              },
              chunkIndex: {
                  type: "number",
                  minimum: 1,
                  description: "Which chunk to retrieve (1-based index)"
              }
          },
          required: ["cacheKey", "chunkIndex"]
      }
  },

• lib/fixed-mcp-tool.js:217-219 (registration)

  Registration via ListToolsRequestSchema handler returning the tools array which includes the fetch-chunk tool definition.

  server.setRequestHandler(ListToolsRequestSchema, async () => {
      return { tools };
  });

• lib/fixed-geminiExecutor.js:368-391 (helper)

  Core helper function implementing chunk retrieval logic from in-memory Map cache, validates existence and index, returns chunk metadata including hasMore flag.

  export function getChunkedEdits(cacheKey, chunkIndex) {
      try {
          const chunks = getChunks(cacheKey);
          if (!chunks || chunks.length === 0) {
              throw new Error('No cached chunks found for the provided cache key');
          }
          
          const chunk = chunks[chunkIndex - 1]; // Convert to 0-based index
          if (!chunk) {
              throw new Error(`Chunk ${chunkIndex} not found. Available chunks: 1-${chunks.length}`);
          }
          
          return {
              content: chunk,
              chunk: chunkIndex,
              totalChunks: chunks.length,
              cacheKey: cacheKey,
              hasMore: chunkIndex < chunks.length
          };
      } catch (error) {
          console.error(`Failed to retrieve chunk: ${error.message}`);
          throw error;
      }
  }

• lib/fixed-geminiExecutor.js:66-68 (helper)

  Simple cache getter utility used by getChunkedEdits.

  function getChunks(key) {
      return chunkCache.get(key) || [];
  }

• lib/fixed-geminiExecutor.js:62-64 (helper)

  Simple cache setter utility used during changeMode chunking in executeGeminiCLI.

  function cacheChunks(key, chunks) {
      chunkCache.set(key, chunks);
  }