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Merged
lifeizhou-ap merged 3 commits into from
Jan 8, 2026
Merged

added validation and debug for invalid call tool result #6368

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92e26e9
added validation and debug for invalid call tool result
lifeizhou-ap Jan 7, 2026
8e5e6cf
fmt
lifeizhou-ap Jan 7, 2026
0fdf5f0
change test function name
lifeizhou-ap Jan 7, 2026
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3 changes: 3 additions & 0 deletions crates/goose/src/agents/agent.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@ use crate::conversation::message::{
ActionRequiredData, Message, MessageContent, ProviderMetadata, SystemNotificationType,
ToolRequest,
};
use crate::conversation::tool_result_serde::call_tool_result;
use crate::conversation::{debug_conversation_fix, fix_conversation, Conversation};
use crate::mcp_utils::ToolResult;
use crate::permission::permission_inspector::PermissionInspector;
Expand Down Expand Up @@ -1123,6 +1124,8 @@ impl Agent {

match item {
ToolStreamItem::Result(output) => {
let output = call_tool_result::validate(output);

if enable_extension_request_ids.contains(&request_id)
&& output.is_err()
{
Expand Down
2 changes: 1 addition & 1 deletion crates/goose/src/conversation/mod.rs
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Expand Up @@ -6,7 +6,7 @@ use thiserror::Error;
use utoipa::ToSchema;

pub mod message;
mod tool_result_serde;
pub mod tool_result_serde;

#[derive(Debug, Clone, Serialize, Deserialize, ToSchema, PartialEq)]
pub struct Conversation(Vec<Message>);
Expand Down
95 changes: 94 additions & 1 deletion crates/goose/src/conversation/tool_result_serde.rs
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Expand Up @@ -102,7 +102,17 @@ pub mod call_tool_result {
},
}

let format = ResultFormat::deserialize(deserializer)?;
let original_value = serde_json::Value::deserialize(deserializer)?;

let format = ResultFormat::deserialize(&original_value).map_err(|e| {
tracing::debug!(
"Failed to deserialize call_tool_result: {}. Original data: {}",
e,
serde_json::to_string(&original_value)
.unwrap_or_else(|_| "<invalid json>".to_string())
);
serde::de::Error::custom(e)
})?;

match format {
ResultFormat::NewSuccess { status, value } => {
Expand Down Expand Up @@ -141,4 +151,87 @@ pub mod call_tool_result {
}
}
}

pub fn validate(result: ToolResult<CallToolResult>) -> ToolResult<CallToolResult> {
match &result {
Ok(call_tool_result) => match serde_json::to_string(call_tool_result) {
Ok(json_str) => match serde_json::from_str::<CallToolResult>(&json_str) {
Ok(_) => result,
Err(e) => {
tracing::error!("CallToolResult failed validation by deserialization: {}. Original data: {}", e, json_str);
Err(ErrorData {
code: ErrorCode::INTERNAL_ERROR,
message: Cow::from(format!("Tool result validation failed: {}", e)),
data: None,
})
}
},
Err(e) => {
tracing::error!("CallToolResult failed serialization: {}", e);
Err(ErrorData {
code: ErrorCode::INTERNAL_ERROR,
message: Cow::from(format!("Tool result serialization failed: {}", e)),
data: None,
})
}
},
Comment on lines +157 to +177
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Copilot AI Jan 7, 2026

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This validation performs an unnecessary serialize->deserialize round-trip. Since CallToolResult is from the rmcp crate which performs validation during deserialization, you can validate directly by checking if content is empty and structured_content is None, matching the MCP standard constraint mentioned in the PR description.

Suggested change
Ok(call_tool_result) => match serde_json::to_string(call_tool_result) {
Ok(json_str) => match serde_json::from_str::<CallToolResult>(&json_str) {
Ok(_) => result,
Err(e) => {
tracing::error!("CallToolResult failed validation by deserialization: {}. Original data: {}", e, json_str);
Err(ErrorData {
code: ErrorCode::INTERNAL_ERROR,
message: Cow::from(format!("Tool result validation failed: {}", e)),
data: None,
})
}
},
Err(e) => {
tracing::error!("CallToolResult failed serialization: {}", e);
Err(ErrorData {
code: ErrorCode::INTERNAL_ERROR,
message: Cow::from(format!("Tool result serialization failed: {}", e)),
data: None,
})
}
},
Ok(call_tool_result) => {
let has_empty_content = call_tool_result.content.is_empty();
let has_no_structured_content = call_tool_result.structured_content.is_none();
if has_empty_content && has_no_structured_content {
tracing::error!(
"CallToolResult failed validation: content must not be empty when structured_content is None"
);
Err(ErrorData {
code: ErrorCode::INTERNAL_ERROR,
message: Cow::from(
"Tool result validation failed: content must not be empty when structured_content is None",
),
data: None,
})
} else {
result
}
}

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@lifeizhou-ap lifeizhou-ap Jan 7, 2026

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we could, but it introduced duplicated logic in goose and rmcp. So it would be good to reuse the deserialization function in rmcp to use it as source of truth

Err(_) => result,
}
}
}

#[cfg(test)]
mod tests {
use super::*;
use rmcp::model::{CallToolResult, Content, ErrorCode, ErrorData};
use std::borrow::Cow;
#[test]
fn test_validate_accepts_valid_call_tool_result() {
let valid_result = CallToolResult {
content: vec![Content::text("test")],
is_error: Some(false),
structured_content: None,
meta: None,
};

let tool_result: ToolResult<CallToolResult> = Ok(valid_result);
let validated = call_tool_result::validate(tool_result);

assert!(
validated.is_ok(),
"Expected validation to pass for valid CallToolResult"
);
}
#[test]
fn test_validate_returns_error_for_invalid_calltoolresult() {
let valid_result = CallToolResult {
content: vec![],
is_error: Some(false),
structured_content: None,
meta: None,
};

let tool_result: ToolResult<CallToolResult> = Ok(valid_result);
let validated = call_tool_result::validate(tool_result);

assert!(validated.is_err());
assert!(validated
.unwrap_err()
.message
.contains("Tool result validation failed"))
}

#[test]
fn test_validate_passes_through_errors() {
let error_result: ToolResult<CallToolResult> = Err(ErrorData {
code: ErrorCode::INTERNAL_ERROR,
message: Cow::from("test error"),
data: None,
});

let validated = call_tool_result::validate(error_result.clone());

assert!(validated.is_err());
assert_eq!(validated.unwrap_err().message, "test error");
}
}
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