6.5. MCP Server — AI Tool Integration

The daslang MCP server exposes 28 compiler-backed tools to AI coding assistants via the Model Context Protocol. It provides compilation diagnostics, type inspection, go-to-definition, find-references, AST dump, AOT generation, expression evaluation, parse-aware grep, and more.

Uses stdio transport – no extra build dependencies.

Quick start
Tools
ast-grep / tree-sitter setup
Architecture
Protocol
Configuring Claude Code permissions

6.5.1. Quick start 

Test the server manually:

# Windows
bin/Release/daslang.exe utils/mcp/main.das

# Linux
./bin/daslang utils/mcp/main.das

Configure in .mcp.json (project root):

{
  "mcpServers": {
    "daslang": {
      "command": "bin/Release/daslang.exe",
      "args": ["utils/mcp/main.das"]
    }
  }
}

Or add via CLI:

claude mcp add daslang -- bin/Release/daslang.exe utils/mcp/main.das

Claude Code starts and stops the server automatically with each session.

6.5.2. Tools 

The server exposes 28 tools. Each tool is invoked via MCP’s tools/call method.

6.5.2.1. Compilation and diagnostics 

Tool	Description
`compile_check`	Compile a `.das` file and return errors/warnings plus a categorized function listing on success. Optional `json` for structured output.
`list_functions`	Compile a `.das` file and list all user functions, class methods, and generic instances (after macro expansion).
`list_types`	Compile a `.das` file and list all structs, classes (with fields), enums (with values), and type aliases.
`list_requires`	Compile a `.das` file and list all `require` dependencies (direct and transitive), with source file paths. Optional `json` for structured output.
`list_modules`	List all available daslang modules (builtin C++ modules and daslib). Optional `json` for structured output.
`list_module_api`	List all functions, types, enums, and globals exported by a builtin or daslib module. Optional `compact` mode for large modules, `filter` for substring matching, `section` to limit output (e.g. `functions`, `structs`).

6.5.2.2. Code navigation 

Tool	Description
`goto_definition`	Given a cursor position (file, line, column), resolve the definition of the symbol under the cursor. Returns location, kind, and source snippet.
`type_of`	Given a cursor position, return the resolved type of the expression under the cursor (innermost to outermost).
`find_references`	Find all references to the symbol under the cursor. Scope: `file` (default) or `all` (all loaded modules).
`find_symbol`	Cross-module symbol search (functions, generics, structs, handled types, enums, globals, typedefs, fields). Case-insensitive substring by default; `=query` for exact match.

Cursor-based tools (goto_definition, type_of, find_references) support a no_opt parameter that disables compiler optimizations to preserve the full AST – useful when globals, enum values, or bitfield constants get constant-folded away.

6.5.2.3. Program introspection 

Tool	Description
`ast_dump`	Dump AST of an expression or compiled function. `mode=ast` returns S-expression, `mode=source` returns post-macro daslang code. Optional `lineinfo`.
`program_log`	Produce full post-compilation program text (like `options log`). Shows all types, globals, and functions after macro expansion. Optional `function` filter.
`describe_type`	Describe a type’s fields, methods, values, and base type. Supports structs, classes, handled types, enums, bitfields, variants, tuples, typedefs.

6.5.2.4. Execution 

Tool	Description
`run_script`	Run a `.das` file or inline code snippet and return stdout/stderr.
`run_test`	Run dastest on a `.das` test file and return pass/fail results. Optional `json` for structured output.
`eval_expression`	Evaluate a daslang expression and return its printed result. Supports module imports via `require` parameter.

6.5.2.5. Code generation and transformation 

Tool	Description
`format_file`	Format a `.das` file using the built-in formatter.
`convert_to_gen2`	Convert a `.das` file from gen1 syntax to gen2 using `das-fmt`. Optional `inplace` flag.
`aot`	Generate AOT (ahead-of-time) C++ code for a `.das` file or a single function. Overloaded names return a disambiguation list.

6.5.2.6. Parse-aware search (tree-sitter)

Tool	Description
`grep_usage`	Parse-aware symbol search across `.das` files using ast-grep + tree-sitter. Finds identifier occurrences excluding comments and strings. Conditional on `sg` CLI.
`outline`	List all declarations in a file or set of files using tree-sitter. Works on broken/incomplete code – no compilation needed. Conditional on `sg` CLI.

6.5.2.7. Live-reload control 

These tools interact with a running daslang-live instance via its REST API. All accept an optional port parameter (default 9090).

Tool	Description
`live_launch`	Launch `daslang-live.exe` on a script if not already running. Sets working directory to the script’s folder.
`live_status`	Query the running instance for fps, uptime, paused state, and error status.
`live_error`	Retrieve the last compilation error (plain text).
`live_reload`	Trigger an incremental or full reload.
`live_pause`	Pause or unpause execution.
`live_command`	Dispatch a `[live_command]` by name with JSON arguments.
`live_shutdown`	Gracefully shut down the running instance.

6.5.3. ast-grep / tree-sitter setup 

The grep_usage and outline tools use ast-grep (sg CLI) with a custom tree-sitter grammar for daslang. The sgconfig.yml config file is platform-specific (shared library extension differs), so it is gitignored.

Copy the appropriate template to sgconfig.yml in the project root:

# Windows
cp sgconfig.yml.windows sgconfig.yml

# Linux
cp sgconfig.yml.linux sgconfig.yml

# macOS
cp sgconfig.yml.osx sgconfig.yml

6.5.4. Architecture 

Each tool invocation runs in a separate thread with its own context/heap – when the thread ends, its memory is freed without GC.
Protocol logic lives in protocol.das, the entry point is main.das.
Heap is collected after each request when over threshold (1 MB).
Tool handlers are modular: each tool lives in tools/*.das, shared utilities in tools/common.das.

6.5.5. Protocol 

The server implements MCP via JSON-RPC 2.0 over stdio:

Reads newline-delimited JSON (NDJSON) from stdin.
Writes JSON-RPC responses to stdout (one line per message).
Handles: initialize, tools/list, tools/call, ping.
Logs to stderr and to utils/mcp/mcp_server.log.
File paths passed to tools are resolved relative to the server’s working directory.

6.5.6. Configuring Claude Code permissions 

Optionally, allow all MCP tools without prompting by adding to .claude/settings.json:

{
  "permissions": {
    "allow": [
      "mcp__daslang__compile_check",
      "mcp__daslang__list_functions",
      "mcp__daslang__list_types",
      "mcp__daslang__run_test",
      "mcp__daslang__format_file",
      "mcp__daslang__run_script",
      "mcp__daslang__ast_dump",
      "mcp__daslang__list_modules",
      "mcp__daslang__find_symbol",
      "mcp__daslang__list_requires",
      "mcp__daslang__list_module_api",
      "mcp__daslang__convert_to_gen2",
      "mcp__daslang__goto_definition",
      "mcp__daslang__type_of",
      "mcp__daslang__find_references",
      "mcp__daslang__program_log",
      "mcp__daslang__eval_expression",
      "mcp__daslang__describe_type",
      "mcp__daslang__grep_usage",
      "mcp__daslang__outline",
      "mcp__daslang__aot"
    ]
  }
}