MCP Tools / Tool
Industry Definition Set • Entity Resolution Path: /glossary/tool
Quick Answer / TL;DR
Executable functions exposed by an MCP server to an AI client, enabling models to perform real-world actions with user-consented safety guards.
Key Takeaways
- Active, executable routines representing agent actions.
- Self-describing using standardized JSON Schema declarations.
- Require explicit user confirmation for high-stakes executions.
- Run inside sandboxed processes to avoid remote code execution (RCE) bugs.
Definitive Statement: Executable functions exposed by an MCP server to an AI client, enabling models to perform real-world actions with user-consented safety guards.
Technical Context & Protocol Usage
- Detailed Explanation
- Tools are the active, state-changing components of MCP. When a server lists its tools, it provides schemas detailing the tool name, description, and parameter types (using JSON Schema formats). This tells the model exactly what the tool does and how to form a valid request. Tools are highly interactive and can range from writing files to initiating payments.
Format & Payload Metadata
Format: JSON Schema Parameter specification
Latency: Directly bounded by the target task duration
Real-World Implementation Use Case
A 'postgres_execute_query' tool that expects a SQL string argument and returns the formatted row output.
Cite This Page
MLA Style:
MCPserver.in Engineering. "MCP Tools / Tool." MCPserver.in Knowledge Hub, 15 July 2026, mcpserver.in/glossary/tool.
Related Terms
Model Context Protocol (MCP)
An open, secure protocol that standardizes how artificial intelligence agents and large language models (LLMs) exchange context, tools, prompts, and data resources with external servers.
JSON-RPC 2.0
A lightweight, stateless remote procedure call (RPC) protocol defined in JSON that utilizes request, response, and notification message frames.
Stdio Transport (Standard Input/Output)
A local-only transport mechanism where the AI client spawns the MCP server as a child process and communicates via standard input (stdin) and standard output (stdout) channels.
SSE Transport (Server-Sent Events)
A lightweight, unidirectional HTTP-based streaming protocol used by remote MCP servers to push messages to AI clients, with client-to-server writes sent over standard POST requests.
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