**AI Chat - Tool Executions (counters, tagged with model)**
ai-chat/tool-execution-succeeded: number of tool calls invoked by the AI
that completed without error
ai-chat/tool-execution-failed: number of tool calls invoked by the AI
that threw an error
**AI Chat - Token Usage (counters, tagged with model)**
ai-chat/input-tokens: total input tokens sent to the model across all
turns
ai-chat/output-tokens: total output tokens generated by the model
ai-chat/cache-read-tokens: input tokens served from the model's prompt
cache (cheaper)
ai-chat/cache-write-tokens: input tokens written into the prompt cache
for future reuse
**AI Chat - Latency (histograms in ms, tagged with model)**
ai-chat/turn-latency-ms: total duration of a full chat turn (from stream
start to stream end)
ai-chat/step-latency-ms: duration of a single reasoning/tool-call step
within a turn
ai-chat/ttft-ms: time-to-first-token, i.e. how long until the model
starts streaming output
**MCP - Tool Executions (counters)**
mcp/tool-execution-succeeded: number of MCP tool calls that completed
successfully
mcp/tool-execution-failed: number of MCP tool calls that threw an error
