@ai-sdk/devtools

Intercepts and logs all LLM API calls and responses in real-time by wrapping the AI SDK's language model clients. Captures request payloads (model, temperature, messages, system prompts), response metadata (tokens, latency, finish reason), and error states without modifying application code. Uses a middleware pattern that hooks into the SDK's client initialization to transparently observe all model interactions.

Captures and visualizes the complete lifecycle of tool/function calls made by the LLM, including the tool schema sent to the model, the LLM's decision to invoke a tool, the arguments generated, execution results, and how those results feed back into subsequent LLM calls. Reconstructs the call graph to show dependencies and sequencing of multi-step tool interactions.

Provides a local web dashboard (typically running on localhost:3000 or similar) that renders LLM requests, responses, tool calls, and multi-step interactions in a human-readable, hierarchical format. Uses a client-server architecture where the devtools server collects telemetry from the AI SDK and serves a React/Vue-based frontend that displays interactions with filtering, search, and detail expansion capabilities.

Tracks and visualizes the complete sequence of interactions in multi-turn conversations and agent loops, showing how each LLM response leads to tool calls, which produce results that feed back into the next LLM call. Maintains a timeline view that shows the order and nesting of interactions, including parallel branches where multiple tools are called simultaneously.

Integrates with AI SDK applications through a simple middleware pattern that requires minimal code changes — typically just importing the devtools module and calling an initialization function. The middleware automatically hooks into all AI SDK client instances without requiring explicit instrumentation of individual API calls. Uses dependency injection or module-level patching to intercept calls transparently.

Captures and displays streaming LLM responses in real-time, showing tokens as they arrive and aggregating them into the final response. Tracks streaming metadata such as token counts, finish reasons, and any errors that occur during the stream. Reconstructs the complete response from individual stream chunks for inspection in the UI.

Automatically captures and logs all errors, failures, and exceptional states that occur during LLM interactions, including API errors, timeout errors, tool execution failures, and validation errors. Preserves the full error context (stack traces, error messages, request state) and associates errors with their triggering interactions for root cause analysis.

Collects and aggregates performance metrics for all LLM interactions, including latency (time from request to response), token counts (input and output), and cost estimates based on model pricing. Provides summary statistics (min, max, average, percentiles) across multiple interactions and breakdowns by model, tool, or interaction type.