What causes "{} must be at least 4096" in aaif-goose/goose?

Set the variable to 4096 or higher (e.g. GOOSE_PLANNER_CONTEXT_LIMIT=8192)

{} must be at least 4096

Error message

{} must be at least 4096

What it means

GOOSE_PLANNER_CONTEXT_LIMIT, when set, must parse as usize and be at least 4096 tokens. Smaller values are rejected because the planner needs a floor of context to function; the env var name is interpolated into the message.

Source

Thrown at crates/goose-cli/src/session/mod.rs:2717

            .expect("No provider configured. Run 'goose configure' first")
    };

    // Try planner-specific model first, fall back to default model
    let model = if let Ok(model) = config.get_param::<String>("GOOSE_PLANNER_MODEL") {
        model
    } else {
        println!("WARNING: GOOSE_PLANNER_MODEL not found. Using default model...");
        config
            .get_goose_model()
            .expect("No model configured. Run 'goose configure' first")
    };

    let planner_context_limit = match env::var(GOOSE_PLANNER_CONTEXT_LIMIT)
        .ok()
        .map(|v| v.parse::<usize>())
    {
        Some(Ok(n)) if n >= 4096 => Some(n),
        Some(Ok(_)) => anyhow::bail!("{} must be at least 4096", GOOSE_PLANNER_CONTEXT_LIMIT),
        Some(Err(e)) => anyhow::bail!("{}: {}", GOOSE_PLANNER_CONTEXT_LIMIT, e),
        None => None,
    };

    let model_config =
        goose::model_config::model_config_from_user_config(&provider, model.as_str())?
            .with_context_limit(planner_context_limit);
    let extensions = goose::config::extensions::get_enabled_extensions_with_config(config);
    let reasoner = create(&provider, extensions).await?;

    Ok((reasoner, model_config))
}

/// Format elapsed time duration
/// Shows seconds if less than 60, otherwise shows minutes:seconds
fn format_elapsed_time(duration: std::time::Duration) -> String {
    let total_secs = duration.as_secs();
    if total_secs < 60 {

View on GitHub (pinned to 3810898a74)

Solutions

Set the variable to 4096 or higher (e.g. GOOSE_PLANNER_CONTEXT_LIMIT=8192)
Unset the variable to use the model's default context limit

Example fix

# before
export GOOSE_PLANNER_CONTEXT_LIMIT=1024
# after
export GOOSE_PLANNER_CONTEXT_LIMIT=8192   # or: unset GOOSE_PLANNER_CONTEXT_LIMIT

Defensive patterns

Strategy: validation

Validate before calling

const MIN: usize = 4096;
if let Ok(v) = std::env::var("GOOSE_PLANNER_CONTEXT_LIMIT") {
    let n: usize = v.parse().expect("GOOSE_PLANNER_CONTEXT_LIMIT must be a number");
    assert!(n >= MIN, "GOOSE_PLANNER_CONTEXT_LIMIT must be >= {}", MIN);
}

Prevention

Validate the env var at script start, not after goose fails
Unset the variable when the default limit is acceptable
Remember 4096 is the hard floor for the planner

When it happens

Trigger: Exporting GOOSE_PLANNER_CONTEXT_LIMIT=1024 (or any value below 4096) before any command that builds the planner, such as entering plan mode.

Common situations: Tuning copied from stale docs with a too-small number; leftover experimental values in a shell profile or .env.

Related errors

AI-assisted analysis of aaif-goose/goose@3810898a74 (2026-08-16). Data as JSON: /api/errors/98715aab34c71f44. Report an issue: GitHub.