call-tool
Execute a specific tool from a designated MCP server by providing the server name, tool name, and arguments. Use after identifying tools with find-tools.
Instructions
Call a specific tool from a specific server. TIP: Use find-tools first to discover the tool and get the correct serverName and toolName
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| serverName | Yes | Name of the MCP server to call tool from | |
| toolArgs | Yes | Arguments to pass to the tool | |
| toolName | Yes | Name of the tool to call |
Implementation Reference
- src/index.ts:105-133 (handler)Handler function for the 'call-tool' tool. Destructures arguments, calls serverManager.callTool, and returns the result as JSON text content or an error.
async (args, extra) => { try { const { serverName, toolName, toolArgs } = args; const result = await serverManager.callTool( serverName, toolName, toolArgs, ); return { content: [ { type: "text", text: JSON.stringify(result, null, 2), }, ], }; } catch (error) { return { content: [ { type: "text", text: `Tool call failed: ${(error as Error).message}`, }, ], isError: true, }; } }, - src/index.ts:97-134 (registration)Registration of the 'call-tool' tool on the MCP server, including name, description, input schema derived from CallToolParamsSchema, and handler function.
server.tool( "call-tool", "Call a specific tool from a specific server. TIP: Use find-tools first to discover the tool and get the correct serverName and toolName", { serverName: CallToolParamsSchema.shape.serverName, toolName: CallToolParamsSchema.shape.toolName, toolArgs: CallToolParamsSchema.shape.toolArgs, }, async (args, extra) => { try { const { serverName, toolName, toolArgs } = args; const result = await serverManager.callTool( serverName, toolName, toolArgs, ); return { content: [ { type: "text", text: JSON.stringify(result, null, 2), }, ], }; } catch (error) { return { content: [ { type: "text", text: `Tool call failed: ${(error as Error).message}`, }, ], isError: true, }; } }, ); - src/types.ts:49-61 (schema)Zod schema defining the input parameters for the 'call-tool' tool: serverName (string), toolName (string), toolArgs (record of unknown).
export const CallToolParamsSchema = z.object({ serverName: z .string() .describe("Name of the MCP server to call tool from"), toolName: z.string().describe("Name of the tool to call"), toolArgs: z .record(z.unknown()) .describe("Arguments to pass to the tool"), }); export type CallToolParams = z.infer< typeof CallToolParamsSchema >; - src/server-manager.ts:318-328 (helper)Helper method in McpServerManager class that retrieves the client for the server and calls the target tool using the MCP client SDK.
async callTool( serverName: string, toolName: string, args: Record<string, unknown> ): Promise<any> { const client = this.getClient(serverName); return await client.callTool({ name: toolName, arguments: args, }); }