mcpc – Universal command-line client for Model Context Protocol

Dynamically discovers and establishes connections to Model Context Protocol servers through a unified CLI interface. Implements MCP protocol handshake negotiation, capability advertisement parsing, and connection state management across heterogeneous server implementations. Supports both stdio-based and network transport layers for server communication.

Executes remote MCP tools by marshalling CLI arguments into properly-typed JSON payloads according to server-advertised JSON schemas. Implements argument parsing, type coercion, validation against remote schemas, and error handling for tool execution failures. Supports both positional and named arguments with automatic schema introspection.

Fetches and streams resources (files, documents, data) exposed by MCP servers using URI-based addressing and optional content filtering. Implements resource discovery via server manifests, content type negotiation, and streaming for large payloads to avoid memory exhaustion. Supports both text and binary resource types with appropriate encoding handling.

Executes reusable prompt templates exposed by MCP servers with dynamic variable substitution and context injection. Implements template discovery, argument binding to template parameters, and output formatting for LLM consumption. Supports both simple string interpolation and complex prompt composition with multiple template chaining.

Provides an interactive read-eval-print loop for exploring MCP servers, with command history, tab completion for tool/resource names, and multi-line input support. Implements readline-style editing, persistent history storage, and context awareness for completion suggestions based on connected server capabilities.

Captures and displays raw MCP protocol messages (requests, responses, notifications) for debugging server implementations and client behavior. Implements message logging with optional filtering by message type, pretty-printing of JSON payloads, and timing information for performance analysis. Supports both human-readable and machine-parseable output formats.

Loads and manages MCP server configurations from YAML/JSON files with support for environment variable substitution, profile-based configuration switching, and validation against a schema. Implements configuration inheritance, default value merging, and error reporting for missing or invalid configuration entries.

Implements comprehensive error handling with detailed diagnostic messages, automatic retry logic for transient failures, and graceful degradation when servers are unavailable. Provides error categorization (network, protocol, validation, server-side), suggested remediation steps, and error context preservation for debugging.

Transforms MCP server responses into multiple output formats (JSON, YAML, CSV, plain text, markdown) with optional filtering, sorting, and aggregation. Implements format-specific serialization, pretty-printing with syntax highlighting, and piping to external tools (jq, grep, etc.) for further processing.