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Tools are callable MCP capabilities. They usually represent backend operations such as fetch, search, create, or update. A tool import makes one MCP tool available to the workflow:

Tool schemas

input {} and output {} define the tool contract expected by the workflow.

Runtime bindings

Use bindings {} when the workflow should supply trusted runtime values directly. This is the workflow-owned pattern.
Use workflow-owned calls when the operation is required and should not depend on model discretion.

Agent tool access

Agents can only call tools listed in uses.
This is the model-owned pattern: the model decides whether and when to call available tools.

Choosing the pattern

  • Use workflow-owned calls (dynamic + call tool.*) for deterministic steps and strict ordering.
  • Use model-owned calls (uses: [tool.*]) when the model needs tool-choice judgment.
  • Combine both when needed: prefetch core data deterministically, then expose selected tools for reasoning.
uses can also include prompts and resources.

See also