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# Function nemo_relay_register_tool_request_intercept

> Register a tool request intercept. The callback can transform tool arguments before execution. Runs after request guardrails in the middleware pipeline.

Generated from `cargo doc --no-deps -p nemo-relay -p nemo-relay-adaptive -p nemo-relay-ffi`.

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Register a tool request intercept. The callback can transform tool arguments before execution. Runs after request guardrails in the middleware pipeline.

## Parameters

* `name`: Unique intercept name.
* `priority`: Execution priority (lower runs first).
* `break_chain`: If true, stop processing further intercepts after this one.
* `cb`: Transform callback that receives tool name and args JSON, returns modified args JSON.
* `user_data`: Opaque pointer passed to `cb`.
* `free_fn`: Optional destructor for `user_data`.

The callback is fallible. To signal failure, call [`crate::error::nemo_relay_set_last_error_message`](/reference/api/rust-library-reference/nemo-relay-ffi/error/fn-nemo-relay-set-last-error-message) from C and return null.

## Safety

`name` must be a valid C string. `cb` must be a valid function pointer.