Custom Tools
Custom tools let you extend SynapseOrch agents with your own capabilities.
You can register any REST API endpoint or Python function as a first-class tool that agents can call just like any native tool.
Two types of custom tools
| Type | Description |
|---|---|
| REST API Tool | Wrap any HTTP endpoint as an agent tool — including an n8n workflow's webhook |
| Python Tool | Define a Python function that runs in the sandbox |
You can also create many REST API tools at once by importing an OpenAPI spec.
How they work
Custom tools are stored in SynapseOrch's database. An agent can call a custom tool when its tool list names the tool, names the tool's group (group:<id>), or is all.
The agent sees:
- The tool's Name and Description (self-hosted, System Name (Snake Case) and Description (For AI))
- Its Input schema — the arguments it must pass
It doesn't know (or need to know) whether the tool is a REST call, a Python function, or an MCP server tool — it just calls it. What it gets back is the tool's response.
Managing custom tools
Open Apps › Tools to:
- View all registered tools, marked with their HTTP method (self-hosted, HTTP · POST and the like, or n8n) or Python
- Create one with New tool — choose HTTP request for a REST API tool or Python code for a Python tool (self-hosted, New Tool, then the editor's HTTP or Python)
- Create several from a spec with Import OpenAPI
- Click a tool to edit it, or delete it
Self-hosted, a Python tool can be tried with sample inputs using Test Run in its editor. REST API tools have no test button; try one from an agent in Chat.
Use cases
- Internal APIs — wrap your company's internal REST endpoints
- Webhook triggers — trigger Slack messages, Jira tickets, or any webhook
- Data pipelines — call data processing scripts
- Domain logic — implement business-specific calculations or lookups
- n8n workflows — call n8n automation flows as agent tools (see n8n integration)
Tool visibility
Enable custom tools on an agent in its Tools section, like any other tool (self-hosted, they are marked CUSTOM). In the agent's JSON:
"tools": ["my_api_tool", "my_python_tool", "vault_write"]A tool group can be granted as a whole, and includes tools added to the group later:
"tools": ["group:billing_api"]"tools": ["all"] includes every custom tool, along with the native and MCP tools. It does not include the SQL tools, which an agent must be given by name.
Time
One tool that answers "what is the date" and "what date is next Friday" — so an agent computes dates instead of guessing them.
REST API Tools
A REST API tool wraps an HTTP endpoint as an agent tool. The agent provides the parameters, SynapseOrch makes the HTTP call, and the response is returned to the agent as the tool result.