xai-org/grok-build · warning · acp::Error

-32602

-32602

Error message

Invalid params: {e}

What it means

In handle_mcp_elicit, the ext.request.params string is deserialized into McpElicitExtRequest; on parse failure the handler logs the error and replies with a JSON-RPC -32602 (InvalidParams) error containing the serde message. The interaction is then aborted (returns false) rather than proceeding to target the agent.

Source

Thrown at crates/codegen/xai-grok-pager/src/app/acp_handler/interactions.rs:25

    let cancelled = xai_grok_tools::mcp_elicitation::McpElicitExtResponse::Cancel;
    if let Ok(raw) = serde_json::value::to_raw_value(&cancelled) {
        response_tx.send(Ok(acp::ExtResponse::new(raw.into()))).ok();
    }
}

pub(crate) fn handle_mcp_elicit(
    ext: xai_acp_lib::AcpArgs<acp::ExtRequest>,
    app: &mut AppView,
) -> bool {
    use crate::views::elicitation_view::ElicitationViewState;
    use xai_grok_tools::mcp_elicitation::McpElicitExtRequest;

    let ext_req: McpElicitExtRequest = match serde_json::from_str(ext.request.params.get()) {
        Ok(r) => r,
        Err(e) => {
            tracing::error!(error = %e, "Failed to parse McpElicitExtRequest");
            ext.response_tx
                .send(Err(acp::Error::new(-32602, format!("Invalid params: {e}"))))
                .ok();
            return false;
        }
    };

    let Some(id) = interaction_target_agent(app, &ext_req.session_id) else {
        tracing::info!(
            session_id = %ext_req.session_id,
            "mcp elicit for a session with no local view; parked for leader replay-on-attach"
        );
        drop(ext.response_tx);
        return false;
    };
    let is_active = is_matched_agent_active(app, id);
    let Some(agent) = app.agents.get_mut(&id) else {
        drop(ext.response_tx);
        return false;
    };

View on GitHub (pinned to bc7f02eddd)

Solutions

1. Validate and correct the client's params JSON against McpElicitExtRequest (required session_id etc.)
2. Align client and server versions so the elicit request schema matches
3. Log the serde error ({e}) to see exactly which field failed and fix it
4. Add client-side validation before sending the extension request

Example fix

// before
let params = json!({ "sessionId": id }); // wrong field name
acp.extMethod("mcp_elicit", params)?;
// after
let params = json!({ "session_id": id });
acp.extMethod("mcp_elicit", params)?;

fn validate_elicit_params(raw: &str) -> Result<(), String> {
    serde_json::from_str::<McpElicitExtRequest>(raw)
        .map(|_| ())
        .map_err(|e| format!("Invalid params: {e}"))
}

match serde_json::from_str::<McpElicitExtRequest>(params) {
    Err(e) => return Err(acp::Error::new(-32602, format!("Invalid params: {e}"))),
    Ok(req) => handle(req),
}

When it happens

Trigger: Calling the mcp/elicit ACP extension method with params that are not valid JSON or do not match McpElicitExtRequest's schema (missing/misspelled fields like session_id, wrong types).

Common situations: Clients sending older/newer param shapes than the handler expects; JSON-encoded payloads double-quoted or truncated; schema drift after a version bump.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Invalid ACP content blocks: {e}
• Invalid ACP content blocks in "content": {e}
• failed to build request: {e}
• response parse error: {e}
• ACP response missing result field

AI-assisted analysis of xai-org/grok-build@bc7f02eddd (2026-08-31). Data as JSON: /api/errors/ddb5202e31cfc136. Report an issue: GitHub.