fix(mcp): handle EmbeddedResource content blocks in tool results - #3655
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zicochaos wants to merge 1 commit into
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fix(mcp): handle EmbeddedResource content blocks in tool results#3655zicochaos wants to merge 1 commit into
zicochaos wants to merge 1 commit into
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MCP tools may return content blocks with type 'resource' (EmbeddedResource) in addition to type 'text' (TextContent). The _make_tool_handler only extracted TextContent blocks, silently dropping EmbeddedResource content and returning empty strings. This affects any MCP server that returns documents as EmbeddedResource (e.g. qmd's get/multi_get tools which return markdown documents with URI metadata). The fix extracts text from both block.text (TextContent) and block.resource.text (EmbeddedResource), with a placeholder for binary resources (blob).
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This was referenced May 22, 2026
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Problem
MCP tools may return content blocks with
type: 'resource'(EmbeddedResource) in addition totype: 'text'(TextContent). The_make_tool_handlerintools/mcp_tool.pyonly extracts TextContent blocks (block.text), silently dropping EmbeddedResource content and returning empty strings to the agent.Impact
Any MCP server that returns documents as EmbeddedResource is affected. For example, qmd's
getandmulti_gettools return markdown documents as EmbeddedResource with URI metadata — these return empty results through Hermes despite the MCP server responding correctly.The bug is in the content extraction loop at line ~1070:
EmbeddedResource blocks have
block.resource.text, notblock.text, so they're silently skipped.Fix
Extract text from both content block types:
block.textfor TextContent (existing behavior)block.resource.textfor EmbeddedResource (new)block.resource.blob)Minimal change — 10 lines added, no new dependencies.