Enum ToolError 

pub enum ToolError {
    NotFound(String),
    InvalidArgs {
        tool: String,
        message: String,
    },
    Unavailable {
        tool: String,
        reason: String,
    },
    Timeout {
        tool: String,
        seconds: u64,
    },
    PermissionDenied(String),
    ExecutionFailed {
        tool: String,
        message: String,
    },
    CapabilityDenied {
        tool: String,
        code: String,
        message: String,
        suppression_key: Option<String>,
        suggested_tool: Option<String>,
        suggested_action: Option<String>,
    },
    ContentMismatch {
        tool: String,
        path: String,
        message: String,
    },
    Other(String),
}

Tool-specific errors with retry strategy metadata.

These are converted to JSON and sent back to the LLM so it can self-correct (e.g. fix a bad path, retry with different args).

Variants

NotFound(String)

InvalidArgs

Fields

tool: String

message: String

Unavailable

Fields

tool: String

reason: String

Timeout

Fields

tool: String

seconds: u64

PermissionDenied(String)

ExecutionFailed

Fields

tool: String

message: String

CapabilityDenied

Fields

tool: String

code: String

message: String

suppression_key: Option<String>

suggested_tool: Option<String>

suggested_action: Option<String>

ContentMismatch

Content-mismatch error — the tool’s expected content (e.g. old_string) did not match the actual file contents, or the file changed between a read and a write (TOCTOU). The message field embeds a 600-char file preview when available so the model can retry with corrected arguments without an extra read_file round-trip.

Numeric code: 1008 (content_mismatch).

Fields

tool: String

Tool that produced the mismatch (e.g. "patch", "write_file").

path: String

Display path of the affected file.

message: String

Human-readable description, optionally including a content preview.

Other(String)

Implementations

impl ToolError

pub fn capability_denied( tool: impl Into<String>, code: impl Into<String>, message: impl Into<String>, ) -> Self

pub fn with_suppression_key(self, suppression_key: impl Into<String>) -> Self

pub fn with_suggested_tool(self, suggested_tool: impl Into<String>) -> Self

pub fn with_suggested_action(self, suggested_action: impl Into<String>) -> Self

pub fn to_llm_payload(&self) -> ToolErrorResponse

pub fn to_llm_payload_enriched( &self, required_fields: Option<Vec<String>>, usage_hint: Option<String>, ) -> ToolErrorResponse

Build an enriched LLM payload with schema-derived corrective hints.

WHY: When the LLM sends invalid arguments, a bare “missing field X” message forces it to guess the full schema from memory. By echoing the required fields and a usage hint, we give it a precise checklist. Hermes-agent’s coerce_tool_args + schema echo pattern reduced retry loops by ~40% in their production telemetry.

pub fn to_llm_response(&self) -> String

Convert to a JSON string suitable for the LLM to parse.

pub fn is_retryable(&self) -> bool

Whether the LLM should retry with different parameters.

pub fn should_suppress_retry(&self) -> bool

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

pub fn code(&self) -> &str

pub fn code_num(&self) -> u16

Numeric error code for fast loop branching.

Maps each variant to a stable integer that survives refactors to the string code. The conversation loop can branch on code_num instead of code.as_str() comparisons for better performance and clarity.

pub fn tool_name(&self) -> Option<&str>

pub fn suggested_tool(&self) -> Option<&str>

pub fn suppression_key(&self) -> Option<String>

pub fn suggested_action(&self) -> Option<&str>

Trait Implementations

impl Debug for ToolError

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

Formats the value using the given formatter.

impl Display for ToolError

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

Formats the value using the given formatter.

impl Error for ToolError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.