> ## Documentation Index
> Fetch the complete documentation index at: https://docs.narrative.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Tool Wire Name Too Long

> A tool wire name exceeds Bedrock's 64-character limit.

**HTTP status:** 400

## When this error occurs

AWS Bedrock's Converse API rejects any tool name longer than 64 characters. The agent loop's
wire name for an MCP tool is the stitched form `{alias}-{tool_name}`; for a caller-declared
tool it's the bare `name`.

In the current implementation:

* **Caller-declared tool names** are validated synchronously at conversation create against
  the 64-char cap (along with dash-free / non-empty rules). A violation surfaces as
  [Invalid Caller-Declared Tool Name](./invalid-caller-tool-name), not this one.
* **MCP tools** are discovered at run start, so the API can't pre-check their wire-name length.
  If a discovered `{alias}-{tool_name}` exceeds 64 chars, Bedrock rejects the inference call
  and the run lands `failed` with a downstream
  [Inference Job Result Decode Failed](./job-result-decode-failed) or
  [MCP Protocol Error](./mcp-protocol-error).

This error class remains in the API for stable docs URLs and possible future use (e.g. a
post-discovery validation step). Current callers shouldn't normally see it.

## How to fix

If you do see it:

* **MCP alias too long** — shorten the alias (`docs` over `verylonglyalias`).
* **MCP tool name too long** — fix it on the MCP server side; you can't rename discovered tools
  client-side.
* **Caller-declared name too long** — shorten the entry in `tools[]`.

Aim for `len(alias) + 1 + len(name) ≤ 64` on the stitched wire form.