Enum Error 

pub enum Error {
    ConnectionFailed {
        server: String,
        source: Box<dyn Error + Send + Sync>,
    },
    SecurityViolation {
        reason: String,
    },
    Timeout {
        operation: String,
        duration_secs: u64,
    },
    SerializationError {
        message: String,
        source: Option<Error>,
    },
    InvalidArgument(String),
    ValidationError {
        field: String,
        reason: String,
    },
    ScriptGenerationError {
        tool: String,
        message: String,
        source: Option<Box<dyn Error + Send + Sync>>,
    },
    ResourceLimitExceeded {
        resource: ResourceKind,
        actual: usize,
        limit: usize,
    },
    DuplicateGeneratedFilePath {
        path: String,
    },
}

Main error type for MCP Code Execution.

All errors in the system use this type, providing consistent error handling across all crates in the workspace.

Variants

ConnectionFailed

MCP server connection failed.

This error occurs when attempting to connect to an MCP server and the connection fails due to network issues, authentication failures, or server unavailability.

Fields

server: String

Name or identifier of the server that failed to connect

source: Box<dyn Error + Send + Sync>

Underlying error cause

SecurityViolation

Security policy violation.

Raised when an operation violates configured security policies, such as attempting to access forbidden resources or exceeding resource limits.

Fields

reason: String

Description of the security violation

Timeout

Timeout error.

Occurs when an operation exceeds its configured timeout limit.

Fields

operation: String

Name of the operation that timed out

duration_secs: u64

Duration in seconds before timeout occurred

SerializationError

Serialization/deserialization error.

Raised when JSON or other data format conversion fails.

Fields

message: String

Description of the serialization failure

source: Option<Error>

Underlying serde error

InvalidArgument(String)

Invalid argument error.

Raised when CLI arguments or function parameters are invalid.

ValidationError

Validation error for domain types.

Raised when creating or validating domain types like SkillName, SkillDescription, etc. that have specific format requirements.

Fields

field: String

The field that failed validation

reason: String

Detailed reason for the validation failure

ScriptGenerationError

Script generation failed.

Raised when generating TypeScript scripts from tool schemas fails.

Fields

tool: String

The tool name that failed to generate

message: String

Description of the generation failure

source: Option<Box<dyn Error + Send + Sync>>

Optional underlying error

ResourceLimitExceeded

A server- or attacker-controlled quantity exceeded a configured upper bound.

Raised when a value that ultimately originates from an untrusted MCP server response (tool count, a tool’s name/description length, its schema size, etc.) exceeds one of the resource-exhaustion (CWE-400) protections in mcp_execution_introspector or mcp_execution_codegen.

Fields

resource: ResourceKind

Which bounded resource was exceeded.

actual: usize

The actual observed size/count that triggered the rejection.

limit: usize

The configured maximum allowed for this resource.

DuplicateGeneratedFilePath

A generated file’s path collides with one already present in the same output.

Raised when adding a file to a generated-code collection would silently overwrite a file already added at the same path — e.g. a tool name that sanitizes to a generator’s own reserved output filename (like index) slipping past name disambiguation and colliding with the fixed index.ts re-export (issue #312).

Fields

path: String

The path that was already present when a second file was added at it.

Implementations

impl Error

pub const fn is_connection_error(&self) -> bool

Returns true if this is a connection error.

Examples

use mcp_execution_core::Error;

let err = Error::ConnectionFailed {
    server: "test".to_string(),
    source: "connection refused".into(),
};
assert!(err.is_connection_error());

pub const fn is_security_error(&self) -> bool

Returns true if this is a security violation error.

Examples

use mcp_execution_core::Error;

let err = Error::SecurityViolation {
    reason: "Unauthorized access".to_string(),
};
assert!(err.is_security_error());

pub const fn is_timeout(&self) -> bool

Returns true if this is a timeout error.

Examples

use mcp_execution_core::Error;

let err = Error::Timeout {
    operation: "execute_code".to_string(),
    duration_secs: 30,
};
assert!(err.is_timeout());

pub const fn is_validation_error(&self) -> bool

Returns true if this is a validation error.

Examples

use mcp_execution_core::Error;

let err = Error::ValidationError {
    field: "skill_name".to_string(),
    reason: "Invalid characters".to_string(),
};
assert!(err.is_validation_error());

pub const fn is_script_generation_error(&self) -> bool

Returns true if this is a script generation error.

Examples

use mcp_execution_core::Error;

let err = Error::ScriptGenerationError {
    tool: "send_message".to_string(),
    message: "Template rendering failed".to_string(),
    source: None,
};
assert!(err.is_script_generation_error());

pub const fn is_resource_limit_exceeded(&self) -> bool

Returns true if this is a resource-limit-exceeded error.

Examples

use mcp_execution_core::{Error, ServerId};
use mcp_execution_core::ResourceKind;

let err = Error::ResourceLimitExceeded {
    resource: ResourceKind::ToolCount {
        server_id: ServerId::new("github").unwrap(),
    },
    actual: 1500,
    limit: 1000,
};
assert!(err.is_resource_limit_exceeded());

pub const fn is_duplicate_generated_file_path(&self) -> bool

Returns true if this is a duplicate-generated-file-path error.

Examples

use mcp_execution_core::Error;

let err = Error::DuplicateGeneratedFilePath {
    path: "index.ts".to_string(),
};
assert!(err.is_duplicate_generated_file_path());

Trait Implementations

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

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.