Token
Industry Definition Set • Entity Resolution Path: /glossary/token
Quick Answer / TL;DR
The fundamental unit of text processed by LLMs, representing a word, subword, or character chunk that the model encodes and decodes.
Key Takeaways
- Fundamental unit of text for LLMs.
- Context windows are measured in tokens.
- Billing is typically per-token for API usage.
- A rough rule of thumb: 1 token ~ 4 characters in English.
Definitive Statement: The fundamental unit of text processed by LLMs, representing a word, subword, or character chunk that the model encodes and decodes.
Technical Context & Protocol Usage
- Detailed Explanation
- Tokens are the building blocks of LLM input and output. A token can be as short as a character or as long as a word, depending on the tokenizer. Models have a context window measured in tokens (e.g., 8K, 128K tokens). When a user sends a prompt, it is tokenized into a sequence of token IDs that the model processes. Billing for most LLM APIs is per-token.
Format & Payload Metadata
Format: Integer IDs mapped to vocabulary entries
Latency: Tokenization is near-instant; model inference scales with token count
Real-World Implementation Use Case
A 1,000-word prompt might be ~1,300 tokens, costing a fraction of a cent at current API rates.
Cite This Page
MLA Style:
MCPserver.in Engineering. "Token." MCPserver.in Knowledge Hub, 20 July 2026, mcpserver.in/glossary/token.
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.
Deploy Secure MCP Clusters
Run remote SSE Model Context Protocol servers in highly secure, fully-managed environment located inside India (Mumbai/Bengaluru).
Deploy Node Now