Update tool overview

Author: aahill

articles/ai-services/agents/how-to/tools/overview.md

@@ -38,4 +38,4 @@ Agents can access multiple tools in parallel. These can be both Azure OpenAI-hos
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 | [Code interpreter](./code-interpreter.md)     | Enables agents to write and run Python code in a sandboxed execution environment.        | ✔️ | ✔️ | ✔️ | ✔️ |
 |[Function calling](./function-calling.md)     | Allows you to describe the structure of functions to an agent and then return the functions that need to be called along with their arguments.        | ✔️ | ✔️ | ✔️ | ✔️ |
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+|[OpenAPI Specification](./openapi-spec.md) | Connect to an external API using an OpenAPI 3.0 specified tool, allowing for scalable interoperability with various applications. | ✔️ | ✔️ | ✔️ | ✔️ |