Hmbown/CodeWhale · warning

MCP HTTP destination requires network approval

Error message

MCP HTTP destination requires network approval

What it means

Network policy evaluation can return Decision::Prompt, meaning the destination requires interactive user approval before connecting. In this synchronous validation path no prompt can be shown, so validate_network_policy throws this error to indicate approval must be obtained beforehand.

Solutions

  1. Pre-approve the host in the network policy (add to allowlist) so evaluate returns Allow
  2. Trigger the approval flow for this host in the UI, then retry the connection
  3. Use a decider implementation that auto-allows known-good hosts for automated environments

Example fix

// before
// policy.evaluate("new-host.example.com", "mcp") == Prompt -> error
// after
policy.approve_host("new-host.example.com", "mcp"); // user consented earlier
// evaluate now returns Allow and the request proceeds
Defensive patterns

Strategy: fallback

Validate before calling

let host = Url::parse(endpoint)?.host_str().unwrap_or_default().to_string();
if let Decision::Prompt = policy.evaluate(&host, "mcp") {
    // trigger interactive approval flow before constructing the client
    approval_ui.request_host_approval(&host, "mcp").await?;
}

Try / catch

match connect(...).await {
    Err(e) if e.to_string().contains("requires network approval") => {
        // surface approval prompt to user, then retry after consent
        approval_ui.request_host_approval(&host, "mcp").await?;
        connect(...).await?
    }
    other => other?,
}

Prevention

When it happens

Trigger: validate_network_policy gets Decision::Prompt from policy.evaluate(host, "mcp") — the host is neither allow-listed nor denied, so policy demands user consent, from either new (initial URL) or client_for_target (redirect target).

Common situations: First-time connection to a new MCP host under an approval-based policy; a redirect to a host the user has not yet approved; running headless/automated where the approval UI never runs.

Understand the failure class

Background: Permission denied / not authorized / 403 Forbidden: access-control rejections when the caller lacks the required role, grant, or ownership — this error's family across 18 libraries.

Related errors

AI-assisted analysis of Hmbown/CodeWhale@73e0f67d83 (2026-09-22). Data as JSON: /api/errors/e8654cf8f06948ec. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/src/mcp/http_client.rs:227

            .context("building guarded MCP HTTP client")?;
        let mut clients = self
            .clients
            .lock()
            .unwrap_or_else(std::sync::PoisonError::into_inner);
        if !proxied && clients.len() < 32 {
            clients.insert(key, client.clone());
        }
        Ok(client)
    }
}

fn validate_network_policy(url: &Url, network_policy: Option<&NetworkPolicyDecider>) -> Result<()> {
    let host = url.host_str().context("MCP URL has no host")?;
    if let Some(policy) = network_policy {
        match policy.evaluate(host, "mcp") {
            Decision::Allow => {}
            Decision::Deny => bail!("MCP HTTP destination blocked by network policy"),
            Decision::Prompt => bail!("MCP HTTP destination requires network approval"),
        }
    }
    Ok(())
}

fn validate_url(url: &Url) -> Result<()> {
    if !matches!(url.scheme(), "http" | "https") || url.host_str().is_none() {
        bail!("MCP HTTP requires an http:// or https:// URL with a host");
    }
    Ok(())
}

fn url_has_credentials(url: &Url) -> bool {
    !url.username().is_empty() || url.password().is_some()
}

impl McpHttpClient {
    async fn public_dns_pin(&self, url: &Url) -> Result<Option<(String, SocketAddr)>> {

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