zed-industries/zed · error · anyhow::Error

Copilot Chat does not support custom tools

Error message

Copilot Chat does not support custom tools

What it means

While converting the request's tools to Copilot Chat format, a tool whose input is not a plain function (e.g. an MCP-style tool) was found; Copilot Chat only accepts function tools, so the request is rejected before it is sent.

Source

Thrown at crates/copilot_chat/src/model.rs:980

                content: message.string_contents(),
            }),
        }
    }

    let tools = request
        .tools
        .iter()
        .map(|tool| match &tool.input {
            language_model::LanguageModelRequestToolInput::Function { input_schema, .. } => {
                Ok(Tool::Function {
                    function: Function {
                        name: tool.name.clone(),
                        description: tool.description.clone(),
                        parameters: input_schema.clone(),
                    },
                })
            }
            language_model::LanguageModelRequestToolInput::Custom { .. } => Err(anyhow::anyhow!(
                "Copilot Chat does not support custom tools"
            )),
        })
        .collect::<Result<Vec<_>>>()?;

    Ok(CopilotChatRequest {
        n: 1,
        stream: model.uses_streaming(),
        temperature: temperature.unwrap_or(0.1),
        model: model.id().to_string(),
        messages,
        tools,
        tool_choice: tool_choice.map(|choice| match choice {
            LanguageModelToolChoice::Auto => ToolChoice::Auto,
            LanguageModelToolChoice::Any => ToolChoice::Required,
            LanguageModelToolChoice::None => ToolChoice::None,
        }),
        thinking_budget: if thinking_allowed && model.supports_thinking() {

View on GitHub (pinned to f4178619ac)

Solutions

1. Exclude non-function tools from Copilot Chat requests
2. Use a model provider that supports the required tool types

When it happens

Trigger: Thrown at crates/copilot_chat/src/model.rs:980 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/08c031ae38336278. Report an issue: GitHub.