What causes "Required: file_path (string), line (int), character (int)." in xai-org/grok-build?

Supply all three arguments: file_path (string), line (int), and character (int) for the requested operation.

Required: file_path (string), line (int), character (int).

Error message

Required: file_path (string), line (int), character (int).

What it means

The LSP tool (`dispatch_tool_typed` in the lsp manager) requires file_path, line, and character for position-based operations such as GoToDefinition, FindReferences, Hover, and GoToImplementation. If any of the three input fields is `None`, the tool returns 'Required: file_path (string), line (int), character (int).' without contacting any language server. It is a pure input-validation error.

Source

Thrown at crates/codegen/xai-grok-tools/src/implementations/lsp/manager.rs:536

        &mut self,
        input: &super::LspToolInput,
    ) -> super::LspToolResult {
        use super::{LspOperation, LspToolResult};

        let err = |msg: String| LspToolResult {
            text: msg,
            is_error: true,
        };

        let result = match input.operation {
            LspOperation::GoToDefinition
            | LspOperation::FindReferences
            | LspOperation::Hover
            | LspOperation::GoToImplementation => {
                let (Some(fp), Some(line), Some(col)) =
                    (&input.file_path, input.line, input.character)
                else {
                    return err("Required: file_path (string), line (int), character (int).".into());
                };
                let path = PathBuf::from(fp);
                let Some(client) = self.client_for_file_mut(&path) else {
                    return err(format!("No LSP server configured for {}", path.display()));
                };
                match input.operation {
                    LspOperation::GoToDefinition => client
                        .goto_definition(&path, line, col)
                        .await
                        .map(|l| format_locations_labeled("Definition", &l)),
                    LspOperation::FindReferences => client
                        .goto_references(&path, line, col)
                        .await
                        .map(|l| format_locations_labeled("References", &l)),
                    LspOperation::GoToImplementation => client
                        .goto_implementation(&path, line, col)
                        .await
                        .map(|l| format_locations_labeled("Implementations", &l)),

View on GitHub (pinned to bc7f02eddd)

Solutions

Supply all three arguments: file_path (string), line (int), and character (int) for the requested operation.
Check which field was missing from the tool input payload and fix the caller that builds the arguments.
Confirm you are using a position-based operation; document/diagnostics-style operations may not need line/character.
Note line/character are typically 0-based LSP positions; verify your editor-derived values are not being dropped as invalid.

Example fix

// before
{ "operation": "hover", "file_path": "src/main.rs" }
// after
{ "operation": "hover", "file_path": "src/main.rs", "line": 10, "character": 4 }

Defensive patterns

Strategy: validation

Validate before calling

// validate tool input before dispatch
function assertPositionArgs(input) {
  const posOps = ["goto_definition", "find_references", "hover", "goto_implementation"];
  if (posOps.includes(input.operation) &&
      !(typeof input.file_path === "string" &&
        Number.isInteger(input.line) &&
        Number.isInteger(input.character))) {
    throw new Error("Required: file_path (string), line (int), character (int).");
  }
}

Type guard

fn has_position(input: &LspToolInput) -> bool {
    input.file_path.is_some() && input.line.is_some() && input.character.is_some()
}

Try / catch

try {
  const locs = await lspTool(input);
} catch (e) {
  if (String(e.message).includes("Required: file_path")) {
    console.error("lsp tool input missing position fields:", input);
  } else { throw e; }
}

Prevention

Always pass file_path, line, and character together for position-based operations
Validate tool-call arguments with a schema before dispatch (agent tool JSON schema)
Remember LSP positions are 0-based; convert editor coordinates before sending
Don't reuse position-less payloads across operations

When it happens

Trigger: Invoking the LSP tool with `operation` set to FindReferences/Hover/GoToDefinition/GoToImplementation (and similar position-based ops) while omitting `file_path`, `line`, or `character` — e.g. only supplying file_path for a Hover call, or line without character (0-based vs 1-based confusion can also cause omitted fields).

Common situations: Agent/LLM constructing incomplete tool arguments; automation scripts assuming defaults for line/character; callers reusing a position-less payload template across operations; off-by-one edits that accidentally zero out or drop fields.

Understand the failure class

Background: Missing required parameter errors: what 'X is required' and 'the required X param is missing' mean, and how to fix them — this error's family across 27 libraries.

Related errors

AI-assisted analysis of xai-org/grok-build@bc7f02eddd (2026-08-31). Data as JSON: /api/errors/354e4423a2288bae. Report an issue: GitHub.