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fix: correctly parse extension name from tool call for MCP apps #6482

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DOsinga merged 1 commit into from
Jan 15, 2026
Merged

fix: correctly parse extension name from tool call for MCP apps #6482

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12 changes: 8 additions & 4 deletions ui/desktop/src/components/ToolCallWithResponse.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -96,10 +96,14 @@ function McpAppWrapper({
}
}

const extensionName =
requestWithMeta.toolCall.status === 'success'
? requestWithMeta.toolCall.value.name.split('__')[0]
: '';
// Tool names are formatted as "{extension_name}__{tool_name}".
// Extension names can contain underscores (special chars like parentheses are normalized to "_"),
// so we must use lastIndexOf to find the delimiter.
// e.g., "my_server(local)" -> "my_server_local_" -> "my_server_local___get_time"
const toolCallName =
requestWithMeta.toolCall.status === 'success' ? requestWithMeta.toolCall.value.name : '';
const delimiterIndex = toolCallName.lastIndexOf('__');
const extensionName = delimiterIndex === -1 ? '' : toolCallName.substring(0, delimiterIndex);
Comment on lines +105 to +106
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@aharvard aharvard Jan 14, 2026

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@DOsinga I think this will work for double parentheses as well.

Since the delimiterIndex is the position of the last _ _ occurrence, this should successfully trim off the tool name while keeping the parentheses-to-underscores conversion intact.

extension(yeah) -> extension_yeah_ __tool_name
extension((yeah)) -> extension__yeah__ __tool_name

Do you agree?

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@DOsinga DOsinga Jan 14, 2026

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eh yeah. but I dont think there's anything stopping authors from putting underscores in toolnames. I think longer term we should just not concat this and then take it apart again (this also makes extension names no unqiue after normalization). we should just pass the original names of extensions and tools around


const toolArguments =
requestWithMeta.toolCall.status === 'success'
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