Fix empty tool results from resource content (e.g. auto visualiser) by DOsinga · Pull Request #7866 · block/goose

DOsinga · 2026-03-13T20:23:33Z

Summary

Fixes #7613 — MCP tools that return Content::resource(...) (like the Auto Visualiser extension) produce empty tool result strings when formatted for LLM APIs, because the formatters only extracted as_text() content. This causes:

Tool results appearing empty to the LLM — the model sees an empty string for tool results that actually contain data (e.g., chart HTML returned as embedded text resources)
API 400 errors — Anthropic's API rejects tool_result blocks with empty content

Changes

Resource content extraction in provider formatters

Anthropic format: Extract text from both Content::Text and Content::Resource (embedded text resources) in tool responses
Snowflake format: Same fix

Empty tool result safety net in conversation repair

Added fix_empty_tool_results pass to the conversation repair pipeline that adds a (empty result) placeholder to tool results with no extractable text content
Added extract_tool_result_text helper that handles both Text and Resource content types

Agent loop cleanup

Simplified final_output_tool lock patterns in the agent loop (cosmetic, same behavior)

Testing

Added tests for tool responses with resource content (Content::embedded_text)
Added tests for mixed text + resource content
Added test for the empty tool result placeholder
Updated existing tests that used empty CallToolResult::success(vec![]) to use realistic content

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chatgpt-codex-connector · 2026-03-13T20:29:25Z

crates/goose/src/providers/formats/anthropic.rs

+                                    if let rmcp::model::ResourceContents::TextResourceContents { text, .. } = &r.resource {
+                                        return Some(text.clone());


Serialize blob tool resources in Anthropic tool_result content

fix_empty_tool_results now considers ResourceContents::BlobResourceContents non-empty via extract_text_from_resource, so blob-only tool results skip placeholder injection, but this formatter only extracts TextResourceContents and drops blob resources. In that case the emitted Anthropic tool_result content is still an empty string, which is the same payload shape Anthropic rejects for empty tool results; this will still fail requests when tools return blob-backed resources (for example base64-encoded file reads).

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jh-block

lgtm but the build seems to be failing

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chatgpt-codex-connector · 2026-03-18T14:42:51Z

crates/goose/src/providers/formats/snowflake.rs

+                                if let Some(r) = c.as_resource() {
+                                    if let rmcp::model::ResourceContents::TextResourceContents {
+                                        text,
+                                        ..
+                                    } = &r.resource


Handle blob resources in Snowflake tool responses

This formatter only extracts TextResourceContents from Content::resource(...), so BlobResourceContents still produce an empty text payload here. Because fix_empty_tool_results now treats blob-backed resources as non-empty, those tool results no longer get a fallback placeholder, and Snowflake requests can silently drop blob-only tool responses (the message is skipped when text_content stays empty), so the model never sees the tool output.

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chatgpt-codex-connector · 2026-03-18T14:42:51Z

crates/goose/src/conversation/mod.rs

+                        let text = extract_tool_result_text(&result.content);
+                        if text.is_empty() {
+                            // Add a placeholder text content so the tool result isn't empty
+                            result.content.push(Content::text("(empty result)"));


Avoid labeling image-only tool results as empty

The new empty-result repair path adds (empty result) whenever extracted text is empty, but extract_tool_result_text only looks at text/resource content and ignores image content. That means image-only tool results are now rewritten as “empty” even when they contain real data, which can mislead downstream model reasoning in providers that already serialize tool images (for example, Google/OpenAI formatters).

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chatgpt-codex-connector · 2026-03-18T14:56:43Z

crates/goose/src/conversation/mod.rs

+fn has_tool_result_content(content: &[Content]) -> bool {
+    content
+        .iter()
+        .any(|c| c.as_text().is_some() || c.as_resource().is_some() || c.as_image().is_some())


Check tool result payload text, not just content variant

has_tool_result_content currently treats any Content::text(...) or Content::resource(...) as non-empty even when the extractable text is "", so fix_empty_tool_results skips adding the placeholder for cases like empty text output or an empty embedded text resource (e.g., reading a 0-byte file). The downstream formatter logic in format_messages (Anthropic and Snowflake) filters out empty extracted strings, so these responses still serialize to empty tool-result content and can still trigger Anthropic 400s or dropped Snowflake tool output.

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- Use extract_text_from_resource in anthropic/snowflake formatters to handle BlobResourceContents (not just TextResourceContents) - Check for image content in fix_empty_tool_results so image-only tool results aren't incorrectly labeled as empty

* origin/main: fix(openai): use Responses API for gpt-5.4 (#7982) Remove lead/worker provider (#7989) chore(release): release version 1.28.0 (#7991) Fix empty tool results from resource content (e.g. auto visualiser) (#7866) Separate SSE streaming from POST work submission (#7834) fix: include token usage in Databricks streaming responses (#7959) Optimize tool summarization (#7938)

* main: (22 commits) feat: add gemini-acp provider, update docs on subscription models + improvements to codex (#8000) fix(openai): use Responses API for gpt-5.4 (#7982) Remove lead/worker provider (#7989) chore(release): release version 1.28.0 (#7991) Fix empty tool results from resource content (e.g. auto visualiser) (#7866) Separate SSE streaming from POST work submission (#7834) fix: include token usage in Databricks streaming responses (#7959) Optimize tool summarization (#7938) fix: overwrite the deprecated googledrive extension config (#7974) refactor: remove unnecessary Arc<Mutex> from tool execution pipeline (#7979) Revert message flush & test (#7966) docs: add Remote Access section with Telegram Gateway documentation (#7955) fix: update webmcp blog post metadata image URL (#7967) fix: clean up OAuth token cache on provider deletion (#7908) fix: hard-coded tool call id in code mode callback (#7939) Fix SSE parsers to accept optional space after data: prefix (#7929) docs: add GOOSE_INPUT_LIMIT to config-files.md (#7961) Add WebMCP for Beginners blog post (#7957) Fix download manager (#7933) Improve the formatting of tool calls, show thinking, treat Reasoning and Thinking as the same thing (sorry Kant) (#7626) ...

…lock#7866) Co-authored-by: Douwe Osinga <[email protected]> Signed-off-by: esnyder <[email protected]>

chatgpt-codex-connector bot reviewed Mar 13, 2026

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DOsinga changed the title ~~Fix crash on empty tool results and handle resource content in tool responses~~ Fix empty tool results from resource content (e.g. auto visualiser) Mar 13, 2026

jh-block approved these changes Mar 16, 2026

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Douwe Osinga added 2 commits March 18, 2026 09:02

What goose said

e2e9f01

Allow empty tool result placeholder issue in MOIM injection

27077db

DOsinga force-pushed the fix-tool-use-empty-crash branch from 5977877 to 27077db Compare March 18, 2026 14:36

chatgpt-codex-connector bot reviewed Mar 18, 2026

View reviewed changes

DOsinga force-pushed the fix-tool-use-empty-crash branch from f16674c to 0b67387 Compare March 18, 2026 18:39

DOsinga added this pull request to the merge queue Mar 18, 2026

Merged via the queue into block:main with commit 0cd41be Mar 18, 2026
21 checks passed

DOsinga deleted the fix-tool-use-empty-crash branch March 18, 2026 19:07

cloorc mentioned this pull request Mar 21, 2026

Track and cherry-pick latest 13 commits till #0ace570e28080f0c5d54a76728245bcf82572967 LeafAI/Leaf#5

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elijahsgh pushed a commit to elijahsgh/goose that referenced this pull request Mar 21, 2026

Fix empty tool results from resource content (e.g. auto visualiser) (b…

2797659

…lock#7866) Co-authored-by: Douwe Osinga <[email protected]> Signed-off-by: esnyder <[email protected]>

elijahsgh pushed a commit to elijahsgh/goose that referenced this pull request Mar 21, 2026

Fix empty tool results from resource content (e.g. auto visualiser) (b…

4bc9317

…lock#7866) Co-authored-by: Douwe Osinga <[email protected]> Signed-off-by: esnyder <[email protected]>

github-actions bot mentioned this pull request Mar 24, 2026

chore(release): release version 1.29.0 #8089

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Fix empty tool results from resource content (e.g. auto visualiser)#7866

Fix empty tool results from resource content (e.g. auto visualiser)#7866
DOsinga merged 3 commits intoblock:mainfrom
DOsinga:fix-tool-use-empty-crash

DOsinga commented Mar 13, 2026 •

edited

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		if let rmcp::model::ResourceContents::TextResourceContents { text, .. } = &r.resource {
		return Some(text.clone());

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DOsinga commented Mar 13, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Changes

Resource content extraction in provider formatters

Empty tool result safety net in conversation repair

Agent loop cleanup

Testing

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DOsinga commented Mar 13, 2026 •

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