charmbracelet/crush · error

error creating prompt: %s

Error message

error creating prompt: %s

What it means

In the agentic_fetch tool's Execute, prompt.NewPrompt('agentic_fetch', agenticFetchPromptTmpl, promptOpts...) fails to compile/validate the embedded prompt template, and the tool returns 'error creating prompt: %s'. This is a programming/template-authoring defect, not a runtime user error.

Source

Thrown at internal/agent/agentic_fetch_tool.go:147

					}
					tempFile.Close()

					fullPrompt = fmt.Sprintf("%s\n\nThe web page from %s has been saved to: %s\n\nUse the view and grep tools to analyze this file and extract the requested information.", params.Prompt, params.URL, tempFilePath)
				} else {
					fullPrompt = fmt.Sprintf("%s\n\nWeb page URL: %s\n\n<webpage_content>\n%s\n</webpage_content>", params.Prompt, params.URL, content)
				}
			} else {
				// Search mode: let the sub-agent search and fetch as needed.
				fullPrompt = fmt.Sprintf("%s\n\nUse the web_search tool to find relevant information. Break down the question into smaller, focused searches if needed. After searching, use web_fetch to get detailed content from the most relevant results.", params.Prompt)
			}

			promptOpts := []prompt.Option{
				prompt.WithWorkingDir(tmpDir),
			}

			promptTemplate, err := prompt.NewPrompt("agentic_fetch", string(agenticFetchPromptTmpl), promptOpts...)
			if err != nil {
				return fantasy.ToolResponse{}, fmt.Errorf("error creating prompt: %s", err)
			}

			_, small, err := c.buildAgentModels(ctx, true)
			if err != nil {
				return fantasy.ToolResponse{}, fmt.Errorf("error building models: %s", err)
			}

			systemPrompt, err := promptTemplate.Build(ctx, small.Model.Provider(), small.Model.Model(), c.cfg)
			if err != nil {
				return fantasy.ToolResponse{}, fmt.Errorf("error building system prompt: %s", err)
			}

			smallProviderCfg, ok := c.cfg.Config().Providers.Get(small.ModelCfg.Provider)
			if !ok {
				return fantasy.ToolResponse{}, errors.New("small model provider not configured")
			}

			webFetchTool := tools.NewWebFetchTool(tmpDir, client)

View on GitHub (pinned to 7944b8e522)

Solutions

1. Validate the agenticFetchPromptTmpl template syntax (parse it in a unit test) and fix the syntax error
2. Rebuild/reinstall the binary if the template is fine but the binary is stale
3. Confirm the promptOpts (working dir) point to a valid directory

Example fix

// before
promptTemplate, err := prompt.NewPrompt("agentic_fetch", string(agenticFetchPromptTmpl), promptOpts...)
if err != nil {
    return fantasy.ToolResponse{}, fmt.Errorf("error creating prompt: %s", err)
}
// after
// add a test that parses the template at startup so bad syntax fails fast:
func TestAgenticFetchPromptParses(t *testing.T) {
    _, err := prompt.NewPrompt("agentic_fetch", string(agenticFetchPromptTmpl), prompt.WithWorkingDir(t.TempDir()))
    require.NoError(t, err)
}

// compile-time guard: parse the template in an init/test
_, err := prompt.NewPrompt("agentic_fetch", string(agenticFetchPromptTmpl), prompt.WithWorkingDir(os.TempDir()))
if err != nil {
    panic(fmt.Sprintf("agentic_fetch template invalid: %v", err))
}

resp, err := tool.Execute(ctx, params)
if err != nil && strings.HasPrefix(err.Error(), "error creating prompt") {
    return reportTemplateBug(err) // developer defect; do not retry
}

When it happens

Trigger: The agenticFetchPromptTmpl text contains invalid template syntax or prompt.NewPrompt rejects the options (e.g. bad working dir) at Execute time when the tool lazily builds its prompt in tmpDir.

Common situations: A developer edited the agentic fetch prompt template and introduced invalid Go template syntax; shipped binary with a malformed embedded template; unusual tmpDir passed via prompt.WithWorkingDir.

Related errors

• parsing template: %w
• executing template: %w
• failed to create parent directories: %w
• session ID is required for creating a new file
• failed to write file: %w

AI-assisted analysis of charmbracelet/crush@7944b8e522 (2026-08-29). Data as JSON: /api/errors/36e5388afefe7754. Report an issue: GitHub.