agentHost: lean tools + CLI-parity prompt for HydraFusion - #339165
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Aashna Garg (aashna) wants to merge 2 commits into
Open
Aashna Garg (aashna) wants to merge 2 commits into
Aashna Garg (aashna) wants to merge 2 commits into
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Default-exclude VS Code-only tools for hydrafusion unless a tool filter is configured, and add CLI tone/search/tool-efficiency prompt sections for hydrafusion (microsoft/vscode-internalbacklog#9756). Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
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Copilot review overview
🟡 Changes recommended
The default profile removes tools still required by workspace attachment, interactive input, and automatic chat-title flows.
Review effort: Balanced
Findings: 1
Open (1)
What changed in this PR
Aligns HydraFusion Agent Host behavior with Copilot CLI by reducing tool-token overhead and applying CLI-oriented prompt guidance.
Changes:
- Adds HydraFusion’s default excluded-tool profile while preserving user overrides.
- Registers HydraFusion-specific tone and tool-efficiency prompt sections.
- Adds tests and contributor documentation.
| File | Description |
|---|---|
common/copilotCliConfig.ts |
Defines HydraFusion’s excluded tools. |
node/copilot/copilotSessionLauncher.ts |
Applies default exclusions during launch/resume. |
node/copilot/prompts/hydraFusionPrompt.ts |
Adds HydraFusion prompt guidance. |
node/copilot/prompts/allPrompts.ts |
Registers the new prompt contributor. |
node/copilot/prompts/AGENTS.md |
Documents HydraFusion behavior. |
test/node/copilotSessionLauncher.test.ts |
Tests tool-filter defaults and overrides. |
test/node/agentHostPromptRegistry.test.ts |
Tests prompt matching and sections. |
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Base:
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The interactive Copilot CLI ships both tools, so keeping them is true parity (42 excluded). Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Aashna Garg (aashna)
marked this pull request as ready for review
October 1, 2026 20:14
| export const HYDRAFUSION_DEFAULT_EXCLUDED_TOOLS: readonly string[] = [ | ||
| 'usages', 'problems', | ||
| 'createJupyterNotebook', 'editNotebook', 'runNotebookCell', 'getNotebookSummary', 'readNotebookCellOutput', | ||
| 'runTask', 'getTaskOutput', 'createAndRunTask', |
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why are we turning these tools off? Feels like we're overfitting for evals here.
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also tool search defers all of these tools. this will break scenarios in Agents window as well.
Bhavya U (bhavyaus)
requested changes
Oct 1, 2026
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Brings HydraFusion cost in the Agent Host in line with Copilot CLI (microsoft/vscode-internalbacklog#9756).
Changes
hydrafusion(59 → 17 tools); usermodelCapabilityOverridesstill win.hydrafusion.system_reminder: the agent host doesn't inject one (artifact guidance lives only in the tool description), so excludingadd_artifact_or_referencealready removes it. No change needed.rename_chatreminder: new sessions use deferred (host-generated) titles, which never inject it. Only restored legacyactiveAgentsessions do, and the title controller can't see the launcher's per-model tool filters, so that path is left unchanged.Results (TerminalBench 2.1, MSBench, 3 replicas/arm)
ask_user/web_fetchare kept here because the interactive CLI ships them.