openclaw - 💡(How to fix) Fix Bug: Foundry DeepSeek V4 tool turns surface DSML text instead of executable tool calls

Summary

microsoft-foundry/deepseek-v4-pro now works for plain chat in OpenClaw, but tool-using/operator turns remain unreliable because DeepSeek/Foundry sometimes emits DSML tool markup as plain assistant text instead of native tool_calls, and the current openai-completions stream path does not recover that text into executable tool calls.

What changed

A prior fix already addressed the earlier request-shaping failure where Foundry rejected DeepSeek-style thinking payloads (400 Unrecognized request argument supplied: thinking). Plain chat/reasoning calls now succeed.

The remaining failure is later in the pipeline: tool intent is sometimes surfaced as text instead of becoming toolCall blocks.

Live evidence

Installed runtime checked locally:

• openclaw --version -> OpenClaw 2026.5.20 (e510042)

Plain response smoke tests succeeded:

• openclaw agent --local --agent main --model microsoft-foundry/deepseek-v4-pro --thinking minimal --message 'Reply with exactly DEEPSEEK_SMOKE_OK' --json
• openclaw agent --local --agent main --model microsoft-foundry/deepseek-v4-pro --thinking medium --message 'Reply with exactly DEEPSEEK_MEDIUM_OK' --json

Tool-use repro against the real CLI/runtime:

openclaw agent --local --agent main --model microsoft-foundry/deepseek-v4-pro --thinking minimal --message 'Call the session_status tool exactly once with sessionKey current and then stop.' --json

Observed assistant payload returned as visible text instead of an executed tool call:

<｜DSML｜tool_calls>
<｜DSML｜invoke name="session_status">
<｜DSML｜parameter name="sessionKey" string="true">current</｜DSML｜parameter>
</｜DSML｜invoke>
</｜DSML｜tool_calls>

A second live variant was malformed/incomplete and omitted the parameter body entirely:

<｜DSML｜tool_calls>
<｜DSML｜invoke name="session_status">
</｜DSML｜invoke>
</｜DSML｜tool_calls>

Subagent/history verification also showed that the tool was not actually executed; the markup was emitted as assistant text.

Source diagnosis

Relevant repo inspected locally at /Users/manos/Code/openclaw.

What the current code does

src/agents/deepseek-text-filter.ts contains createDeepSeekTextFilter() which strips DSML wrapper text from visible output.

src/agents/openai-transport-stream.ts uses that filter in processOpenAICompletionsStream(...), but real tool calls are still created only from native choiceDelta.tool_calls.

So today the behavior is:

• if DeepSeek/Foundry emits native tool_calls, OpenClaw can handle them
• if DeepSeek/Foundry emits DSML tool markup as plain text, OpenClaw currently strips/streams text but does not promote it to toolCall

Why this is likely not just expected model behavior

DeepSeek's own tool-calls docs describe OpenAI-compatible native message.tool_calls as the intended path:

• https://api-docs.deepseek.com/guides/tool_calls

There is also upstream evidence that DeepSeek V4 Pro can intermittently emit tool calls as plain text with tool_calls: null:

• https://github.com/deepseek-ai/DeepSeek-V3/issues/1244

So the remaining problem looks like a combination of:

1. upstream/provider instability in DeepSeek tool emission
2. missing defensive recovery in OpenClaw for DSML/textual tool intent on the openai-completions stream path

Tested patch candidate

I added a conservative local patch in src/agents/openai-transport-stream.ts plus regression tests in src/agents/openai-transport-stream.test.ts that recover the observed DSML form into synthetic toolCall blocks when:

• the DSML block is complete
• the invoke name exists
• parameters or JSON body parse into valid object arguments

Added test coverage for:

• one-chunk observed DSML tool text
• split-chunk observed DSML tool text
• coexistence with existing DeepSeek DSML filtering/native-tool-call tests

Targeted validation passed:

npx vitest run src/agents/openai-transport-stream.test.ts -t "recovers observed DeepSeek DSML parameter tool call|filters DeepSeek DSML content without disturbing native tool calls|keeps DeepSeek DSML state across native tool-call chunks"

Result:

• 2 test files passed
• 8 tests passed
• 0 failures in that targeted set

Important caveat

This is currently a source-tree patch candidate, not a fully validated installed-runtime fix yet. The local openclaw CLI I reproed with is still the installed build and did not automatically pick up the edited source tree, so I have not yet re-validated the runtime end-to-end on a build containing the patch.

Suggested next step

Take this as a bug + patch candidate:

• add a conservative DSML-text-to-toolCall recovery layer in processOpenAICompletionsStream(...) (or a provider-specific wrapper)
• only synthesize a tool call when the DSML block is complete and arguments parse cleanly
• leave malformed/incomplete DSML as plain text
• then validate from an actual build path using the patched source rather than the currently installed binary

Labels / framing suggestion

• bug
• providers
• microsoft-foundry
• deepseek
• streaming
• tool-calls