# `ConduitMcp.Client.Error`
[🔗](https://github.com/nyo16/conduit_mcp/blob/v0.11.0/lib/conduit_mcp/client/error.ex#L1)

The single error type returned by the MCP client.

Every client failure is `{:error, %ConduitMcp.Client.Error{}}`. A tool that
ran and reported `isError: true` is **not** an error: it comes back as
`{:ok, %ConduitMcp.Client.ToolResult{is_error: true}}`.

## Fields

  * `:kind` - one of the closed set in `kinds/0`; match on it.
  * `:reason` - a short machine-readable detail (an atom or a tagged tuple
    such as `{:jsonrpc, -32602}`); varies per kind.
  * `:data` - optional extra context (for example a JSON-RPC error's `data`,
    or the exception an input handler raised). It may hold server-supplied
    content, so `message/1` never renders it.

## Kinds

  * `:timeout` - the request deadline passed.
  * `:transport` - the transport failed (connection refused, bad HTTP status).
  * `:protocol` - the peer broke the protocol, or answered with a JSON-RPC error.
  * `:denied` - the policy or an approver refused the call.
  * `:not_found` - the tool, resource, or prompt is hidden or unknown.
  * `:hook` - a pre- or post-hook failed (fail closed).
  * `:unavailable` - the connection or its cache is gone.
  * `:closed` - the client was closed.
  * `:overloaded` - in-flight or queue limits were reached, or a hub's
    `:max_stdio_servers`.
  * `:input_handler` - a `ConduitMcp.Client.Handler` callback failed during MRTR.
  * `:auth` - authorization is required or failed.
  * `:rate_limited` - the server or a local limiter rejected the request.
  * `:session_expired` - a legacy session ended and could not be renewed.
  * `:mrtr_round_limit` - an MRTR loop hit a round, input, or state cap.
  * `:pagination_cycle` - a list cursor repeated or a pagination cap was hit.
  * `:message_too_large` - a message exceeded the configured byte cap.
  * `:connection_down` - the connection process exited mid-request.

## Secrets

`message/1` renders only the kind and the reason. Binary reasons are
truncated and `ConduitMcp.Client.Secret` values inspect as
`#Secret<redacted>`, so the message is safe to log.

# `kind`

```elixir
@type kind() ::
  :timeout
  | :transport
  | :protocol
  | :denied
  | :not_found
  | :hook
  | :unavailable
  | :closed
  | :overloaded
  | :input_handler
  | :auth
  | :rate_limited
  | :session_expired
  | :mrtr_round_limit
  | :pagination_cycle
  | :message_too_large
  | :connection_down
```

# `t`

```elixir
@type t() :: %ConduitMcp.Client.Error{
  __exception__: true,
  data: term(),
  kind: kind(),
  reason: term()
}
```

# `from_rpc_error`

```elixir
@spec from_rpc_error(term()) :: t()
```

Builds a `:protocol` error from a JSON-RPC error object.

The reason is `{:jsonrpc, code}`; the full object (string keys, including
the server's `message` and `data`) is kept in `:data`. A malformed object
gives reason `:invalid_error_object`.

# `kinds`

```elixir
@spec kinds() :: [kind(), ...]
```

Every valid `:kind`, in documentation order.

# `new`

```elixir
@spec new(kind(), term(), term()) :: t()
```

Builds an error, raising `ArgumentError` when `kind` is not in `kinds/0`.

    iex> ConduitMcp.Client.Error.new(:timeout, :deadline).kind
    :timeout

---

*Consult [api-reference.md](api-reference.md) for complete listing*