Introduction
The Open Tool Calling (OTC) specification is a comprehensive communication protocol for agents calling tools.
We envision a world in which agents can discover and interact with thousands upon thousands of tools in a seamless, interoperable way.
What is Open Tool Calling?
Open Tool Calling is a standardized protocol (opens in a new tab) that enables AI agents to discover and interact with external tools in a consistent, reliable way. It establishes a structured communication framework between agents (clients) and tools (functions or services), creating a unified language for tool definitions, requests, and responses.
At its core, OTC provides:
- A discovery mechanism: Agents can dynamically discover available tools and their capabilities
- Standardized schemas: Clear definitions for tool specifications, input parameters, and output formats
- Consistent error handling: Structured approaches for handling validation issues and execution errors
- Security included: Built-in support for authentication and authorization
Why Open Tool Calling Matters
In today's AI ecosystem, extending AI model capabilities through tools like APIs, external services, and code functions is crucial. However, developers often have to build integrations to these tools manually. This is a time-consuming and error-prone process, and the lack of standardization leads to significant challenges:
- Fragmentation: Every tool provider implements their own calling conventions
- Integration complexity: Developers must learn multiple proprietary formats
- Inconsistent error handling: Each system handles failures differently
- Limited interoperability: Tools from different sources rarely work together seamlessly
OTC solves these challenges by providing a standardized protocol for agents to discover and interact with tools, built on familiar patterns (REST, JSON) that developers already know.
Who Can Use Open Tool Calling?
Agent developers can leverage OTC to build powerful AI applications without having to build each integration by hand.
Tool developers can reach a wide audience by implementing just one interface, thanks to the standardized format of OTC.