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108108| `OTEL_LOG_USER_PROMPTS` | Enable logging of user prompt content (default: disabled) | `1` to enable |
109109| `OTEL_LOG_ASSISTANT_RESPONSES` | Enable logging of assistant response text on `assistant_response` events (default: disabled). When unset, falls back to the value of `OTEL_LOG_USER_PROMPTS`. Requires Claude Code v2.1.193 or later | `1` to enable, `0` to keep redacted |
110110| `OTEL_LOG_TOOL_DETAILS` | Enable logging of tool parameters and input arguments in tool events and trace span attributes: Bash commands, MCP server and tool names, skill names, user-authored workflow names, and tool input. Also enables custom, plugin, and MCP command names on `user_prompt` events (default: disabled). For Claude Desktop's built-in servers, in sessions Claude Desktop owns, `mcp_server_name`/`mcp_tool_name` emit on `tool_decision`/`tool_result` even with the flag off. The exception requires Claude Code v2.1.214 or later | `1` to enable |
111| `OTEL_LOG_TOOL_CONTENT` | Enable logging of tool input and output content in span events (default: disabled). Requires [tracing](#traces-beta). Content is truncated at the content limit (60 KB by default) | `1` to enable |
111| `OTEL_LOG_TOOL_CONTENT` | Enable logging of tool content in the [`tool.output` span event](#tool-output-span-event) (default: disabled). Span attributes carry tool content under [their own gates](#new-context-gates). Requires [tracing](#traces-beta). Content is truncated at the content limit (60 KB by default) | `1` to enable |
112112| `OTEL_LOG_RAW_API_BODIES` | Emit the full Anthropic Messages API request and response JSON as `api_request_body` / `api_response_body` log events (default: disabled). Bodies include the entire conversation history. Enabling this implies consent to everything `OTEL_LOG_USER_PROMPTS`, `OTEL_LOG_TOOL_DETAILS`, and `OTEL_LOG_TOOL_CONTENT` would reveal | `1` for inline bodies truncated at the content limit (60 KB by default), or `file:<dir>` for untruncated bodies on disk with a `body_ref` pointer in the event |
113113| `CLAUDE_CODE_OTEL_CONTENT_MAX_LENGTH` | Content limit: the maximum length of content-bearing attributes such as model responses, tool content, system prompts, and raw API bodies, truncation marker included, in UTF-16 code units (default: 61440, i.e. 60 KB). The default is sized for backends that cap attribute values at 64 KB; raise it only if your backend accepts larger values, or lower it to cut telemetry volume. When an OpenTelemetry SDK attribute limit, `OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT` or one of its logrecord and span variants, is set lower, Claude Code truncates at that smaller value so the `[TRUNCATED ...]` marker stays within the SDK limit. Requires Claude Code v2.1.214 or later | `262144` |
114114| `OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE` | Metrics temporality preference (default: `delta`). Set to `cumulative` if your backend expects cumulative temporality | `delta`, `cumulative` |
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260260| `skill_name` | Skill name for the Skill tool | `OTEL_LOG_TOOL_DETAILS` |
261261| `subagent_type` | Subagent type for the Agent tool or legacy Task tool | `OTEL_LOG_TOOL_DETAILS` |
262262
263When `OTEL_LOG_TOOL_CONTENT=1`, this span also records a `tool.output` span event whose attributes contain the tool's input and output bodies, truncated at the content limit (60 KB by default) per attribute.
263<span id="tool-output-span-event" />**`tool.output` span event on `claude_code.tool`**
264264
265If you set `OTEL_LOG_TOOL_CONTENT=1`, Read and Bash calls can record a `tool.output` span event on the `claude_code.tool` span. Edit and Write calls record one only when you also set `OTEL_LOG_TOOL_DETAILS=1`. That variable isn't scoped to those two tools, so check its [row in the configuration table](#common-configuration-variables) for the arguments it adds elsewhere.
266
267Claude Code writes this event from a tool call's successful return, so a call that raises an error records nothing, whatever the tool. Among the calls that do return, it records no `tool.output` event for:
268
269* A call to any tool other than Read, Edit, Write, and Bash, including MCP tools and WebFetch
270* A Read that returns anything other than file text, such as an image, a PDF, or a re-read of a file whose contents haven't changed
271* An Edit or Write call, unless you also set `OTEL_LOG_TOOL_DETAILS=1`
272
273The event carries these attributes, each truncated at the content limit (60 KB by default). `Gated by` names the variable an attribute needs on top of `OTEL_LOG_TOOL_CONTENT=1`, and for Edit and Write that variable gates the event itself rather than the attribute.
274
275| Attribute | Description | Gated by |
276| -------------- | --------------------------------------------------------------------------------------------------- | ------------------------------------------ |
277| `content` | Text the Read tool returned, or the text a Write call was asked to write | `OTEL_LOG_TOOL_DETAILS` for the Write tool |
278| `output` | Combined output of a Bash command, with stderr interleaved into stdout | |
279| `diff` | Structured patch the Edit tool applied | `OTEL_LOG_TOOL_DETAILS` |
280| `file_path` | Target file path for the Read, Edit, and Write tools, repeating the span attribute of the same name | `OTEL_LOG_TOOL_DETAILS` |
281| `bash_command` | Command string for the Bash tool | `OTEL_LOG_TOOL_DETAILS` |
282
283The parent span's `tool_name` attribute tells you which tool an event came from. An attribute cut at the content limit is accompanied by `<attribute>_truncated` and `<attribute>_original_length`.
284
265285**`claude_code.tool.blocked_on_user`**
266286
267287| Attribute | Description | Gated by |
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299319| `num_non_blocking_error` | Count of hooks that failed without blocking | |
300320| `num_cancelled` | Count of hooks cancelled before completion | |
301321
322<span id="new-context-gates" />
323
302324<Note>
303325 Additional content-bearing attributes such as `new_context`, `system_prompt_preview`, `user_system_prompt`, `tool_input`, and `response.model_output` are emitted only when detailed beta tracing is active. They are not part of the stable span schema.
304326
327 The gate on `new_context` depends on which span carries it, and each copy is truncated at the content limit (60 KB by default). On the `claude_code.tool` span it carries that tool call's result, whatever the tool, and requires `OTEL_LOG_TOOL_CONTENT=1`. On the `claude_code.interaction` span it carries the user prompt, and on the `claude_code.llm_request` span the new user messages and tool results of that request. Both of those require `OTEL_LOG_USER_PROMPTS=1`.
328
305329 `user_system_prompt` additionally requires `OTEL_LOG_USER_PROMPTS=1`. It carries only the system prompt text you provide via the `systemPrompt` SDK option or `--system-prompt` and `--append-system-prompt` flags, truncated at the content limit (60 KB by default), and is emitted once per session rather than per request.
306330</Note>
307331
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13711395* OpenTelemetry export to your backend is opt-in and requires explicit configuration. For Anthropic's separate operational telemetry and how to disable it, see [Data usage](/docs/en/data-usage#telemetry-services)
13721396* Raw file contents and code snippets are not included in metrics or events. Trace spans are a separate data path: see the `OTEL_LOG_TOOL_CONTENT` bullet below
13731397* When authenticated via OAuth, `user.email` is included in telemetry attributes, sent only to the OTel endpoint you configure, never to Anthropic. If this is a concern for your organization, work with your telemetry backend to filter or redact this field
1374* User prompt content is not collected by default. Only prompt length is recorded. To include prompt content, set `OTEL_LOG_USER_PROMPTS=1`
1398* User prompt content is not collected by default. Only prompt length is recorded. To include prompt content, set `OTEL_LOG_USER_PROMPTS=1`. Under detailed beta tracing this variable reaches further than prompt text: it also gates the [`new_context` span attribute](#new-context-gates), which carries tool results on the `claude_code.llm_request` span
13751399* Assistant response text is not collected by default. Only response length is recorded. To include response text, set `OTEL_LOG_ASSISTANT_RESPONSES=1`. Like all OpenTelemetry data from Claude Code, the response text is sent only to the OTel endpoint you configure, never to Anthropic. When this variable is unset, `OTEL_LOG_USER_PROMPTS` is used as a fallback, so set `OTEL_LOG_ASSISTANT_RESPONSES=0` if you want prompt content without response content
13761400* Tool input arguments and parameters are not logged by default. To include them, set `OTEL_LOG_TOOL_DETAILS=1`. For Claude Desktop's built-in servers, in sessions Claude Desktop owns, `tool_decision` and `tool_result` carry the `mcp_server_name`/`mcp_tool_name` pair, host-authored names rather than argument content, even with the flag off. The exception requires Claude Code v2.1.214 or later. This data is sent only to the OTEL endpoint you configure, never to Anthropic. Arguments may still contain sensitive values, so configure your telemetry backend to filter or redact these attributes as needed. When enabled:
13771401 * `tool_result` and `tool_decision` events include a `tool_parameters` attribute with Bash commands, MCP server and tool names, and skill names. Fields such as `full_command` are emitted untruncated
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13781402 * `tool_result` events additionally include a `tool_input` attribute with file paths, URLs, search patterns, and other arguments. Individual values over 512 characters are truncated and the total is bounded to \~4 K characters
13791403 * `user_prompt` events include the verbatim `command_name` for custom, plugin, and MCP commands
13801404 * Trace spans include the same `tool_input` attribute and input-derived attributes such as `file_path`, with the same truncation as `tool_input`
1381* Tool input and output content is not logged in trace spans by default. To include it, set `OTEL_LOG_TOOL_CONTENT=1`. When enabled, span events include full tool input and output content truncated at the content limit (60 KB by default) per attribute. This can include raw file contents from Read tool results and Bash command output. Configure your telemetry backend to filter or redact these attributes as needed
1405* Tool content is not logged in trace spans by default. To include it, set `OTEL_LOG_TOOL_CONTENT=1`. The `claude_code.tool` span then carries a [`tool.output` span event](#tool-output-span-event) with raw file contents and Bash command output, truncated at the content limit (60 KB by default) per attribute. Tool content also reaches spans through [`new_context`, whose gate differs per span](#new-context-gates). Configure your telemetry backend to filter or redact these attributes as needed
13821406* Raw Anthropic Messages API request and response bodies are not logged by default. To include them, set `OTEL_LOG_RAW_API_BODIES` in your shell, user settings, or managed settings. It's ignored in [project and local settings](/docs/en/settings-reference#variables-claude-code-ignores-in-env). The bodies contain the full conversation history, including the system prompt, every prior user and assistant turn, and tool results, so enabling this implies consent to everything the other `OTEL_LOG_*` content flags would reveal. Claude Code always redacts Claude's extended-thinking content from these bodies, regardless of other settings. The value you set determines how Claude Code delivers the bodies:
13831407 * With `=1`, Claude Code emits `api_request_body` and `api_response_body` log events for each API call. The events' `body` attribute carries the JSON-serialized payload, truncated at the content limit (60 KB by default)
13841408 * With `=file:<dir>`, Claude Code writes untruncated bodies to `.request.json` and `.response.json` files under that directory, and the events carry a `body_ref` path instead of the inline body. Ship the directory with a log collector or sidecar rather than through the telemetry stream