deepset-ai--haystack/releasenotes/notes/agent-dynamic-tools-c5ffaeaa56572802.yaml

---
enhancements:
  - |
    Duplicate tool names are now detected at the start of each ``Agent`` step (before the chat generator call)
    instead of only at tool execution, so the error surfaces earlier and the LLM is never sent duplicate tool schemas.
fixes:
  - |
    ``Agent`` now correctly executes tools supplied only at runtime via ``run(tools=...)`` / ``run_async(tools=...)``
    when no tools were provided at initialization. Previously the run stopped after the first LLM call because the
    step guard checked the init-time tools instead of the tools resolved for the run.
  - |
    Initializing an ``Agent`` no longer warms up a ``SearchableToolset``. Previously construction could iterate the
    tools, and ``SearchableToolset`` warms itself up when iterated, so it was warmed up too early. Its warm-up now
    happens only via ``Agent.warm_up()`` or at run time.
  - |
    The ``haystack.agent.run`` tracing span's ``haystack.agent.tools`` tag now reflects the tools actually used for
    the run. Previously it always reported the init-time tools, so it was inconsistent with the run when tools were
    overridden at runtime via ``run(tools=...)`` / ``run_async(tools=...)``.
upgrade:
  - |
    ``Agent`` no longer validates ``exit_conditions`` against tool names at initialization. Exit conditions are now
    evaluated at runtime, so a condition naming a tool that is loaded later — e.g. a tool passed at runtime or one
    discovered by ``SearchableToolset`` — works as expected. Consequently, an unknown exit-condition name no longer
    raises a ``ValueError`` at construction.
  - |
    Tool support is now validated against the tools resolved for each run, not only the tools provided at
    initialization. Passing tools at runtime via ``run(tools=...)`` to a chat generator that does not support tools
    now raises a ``TypeError`` instead of silently ignoring them.