Enum ToolCallErrorCategory 

pub enum ToolCallErrorCategory {
    SchemaValidation,
    ToolError,
    McpServerError,
    HostBridgeError,
    PermissionDenied,
    RejectedLoop,
    ParseAborted,
    Timeout,
    Network,
    Cancelled,
    Unknown,
}

Wire-level classification of a ToolCallUpdate failure. Pairs with the human-readable error string so clients can render each failure type distinctly (e.g. surface a “permission denied” badge, or a different retry affordance for network vs tool_error). The enum is deliberately extensible — unknown is the default when the runtime could not classify a failure.

Variants

SchemaValidation

Host-side validation rejected the args (missing required field, invalid type, malformed JSON).

ToolError

The tool ran and returned an error result (e.g. read_file on a missing path) — distinguished from a transport failure.

McpServerError

MCP transport / server-protocol error.

HostBridgeError

The host bridge returned an error during dispatch.

PermissionDenied

session/request_permission denied by the client, or a policy rule (static or dynamic) refused the call.

RejectedLoop

The harn loop detector skipped this call because the same (tool, args) pair repeated past the configured threshold.

ParseAborted

Streaming text candidate was detected (bare name( or <tool_call> opener) but never resolved into a parseable call: args parsed as malformed, the heredoc body broke, the tag closed without a balanced expression, or the stream ended mid-call. Used by the streaming candidate detector (harn#692) to retract a tool_call candidate that turned out to be prose or syntactically broken so clients can dismiss the in-flight chip.

Timeout

The tool exceeded its time budget.

Network

Transient network / rate-limited / 5xx provider failure.

Cancelled

The tool was cancelled (e.g. session aborted).

Unknown

Default when classification was not performed.

Implementations

impl ToolCallErrorCategory

pub const ALL: [Self; 11]

pub fn is_recoverable(self) -> bool

Whether a rejection in this category is RECOVERABLE by the model on its own — i.e. the call failed because of a fixable slip (bad/missing arguments, malformed tool name) and re-issuing it with the correction is the right next move. Distinguished from a true policy/permission denial, where the model must NOT retry and should pivot or ask. Used by the dispatch primitive to pick a retry-positive vs. don’t-retry feedback body for the model-facing tool result.

pub fn as_str(self) -> &'static str

pub fn from_internal(category: &ErrorCategory) -> Self

Map an internal ErrorCategory (used by the VM’s VmError classification) onto the wire enum. The internal taxonomy is finer-grained — several transient categories collapse onto Network, and the auth/quota family becomes HostBridgeError because at the tool-dispatch boundary those errors come from the bridge transport rather than the tool itself.

Trait Implementations

impl Clone for ToolCallErrorCategory

fn clone(&self) -> ToolCallErrorCategory

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for ToolCallErrorCategory

impl Debug for ToolCallErrorCategory

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ToolCallErrorCategory

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for ToolCallErrorCategory

impl Hash for ToolCallErrorCategory

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ToolCallErrorCategory

fn eq(&self, other: &ToolCallErrorCategory) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for ToolCallErrorCategory

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for ToolCallErrorCategory