Tidewave Tools Usage

Tidewave MCP Tools - CRITICAL PRIORITY FOR ELIXIR DEVELOPMENT

MANDATORY: Use Tidewave MCP Tools (Skill) as Primary Interface

When working with this Elixir/Phoenix/Ash codebase, ALWAYS prioritize Tidewave MCP tools over traditional file system operations. Tidewave provides deep integration with the Elixir runtime and superior code intelligence.

Tool Usage Hierarchy

1. Code Evaluation - ALWAYS Use Tidewave

NEVER use Bash to run Elixir code! Instead use mcp__tidewave__project_eval:

• Test function behavior and debug issues
• Explore modules and their functions
• Access IEx helpers (e.g., exports(Module), h(Module.function))
• Capture IO output
• Pass arguments with the arguments parameter
• Set custom timeout for long-running operations

Example:

• ❌ WRONG: bash: mix run -e "IO.inspect(MyModule.function())"
• ✅ RIGHT: mcp__tidewave__project_eval: code: "IO.inspect(MyModule.function())"

2. Source Code Navigation - Tidewave First

Before using Grep, Glob, or Read for Elixir code:

mcp__tidewave__get_source_location - Find exact file locations instantly

• Works with: Module, Module.function, Module.function/arity
• Find dependencies: "dep:package_name"
• FASTER than grep/glob for known modules

mcp__tidewave__get_docs - Get documentation without reading files

• Module docs: "MyModule"
• Function docs: "MyModule.function/2"
• Callback docs: "c:GenServer.init/1"

Example:

• ❌ WRONG: grep: pattern: "defmodule Worker"
• ✅ RIGHT: mcp__tidewave__get_source_location: reference: "MyApp.Worker"

3. Database Operations - Direct SQL Execution

mcp__tidewave__execute_sql_query - Run SQL directly against Ecto repos

• Inspect database schema
• Query data (limited to 50 rows, use LIMIT/OFFSET for more)
• Supports parameterized queries
• Auto-detects available repositories
• Returns native Elixir data structures

mcp__tidewave__get_ecto_schemas - List all schemas and their locations

• ALWAYS use this before searching for schema files
• Returns module names with file paths

Example:

• ❌ WRONG: bash: psql -c "SELECT * FROM users"
• ✅ RIGHT: mcp__tidewave__execute_sql_query: query: "SELECT * FROM users LIMIT 10"

4. Dependency Documentation

mcp__tidewave__search_package_docs - Search Hex documentation

• Searches project dependencies by default
• Can target specific packages
• Use BEFORE trying to read dependency source code

5. Error Diagnosis

mcp__tidewave__get_logs - Get application logs

• Filter with regex patterns
• Tail recent entries
• Essential for debugging runtime issues

Workflow Patterns

Understanding a Module

1. FIRST: mcp__tidewave__get_docs - Get documentation
2. THEN: mcp__tidewave__get_source_location - Find the file
3. THEN: mcp__tidewave__project_eval with exports(Module) - List functions
4. FINALLY: Read the file if needed for implementation details

Testing Code Changes

1. ALWAYS: Test with mcp__tidewave__project_eval before writing
2. Example: code: "MyModule.new_function(:test_input) |> IO.inspect()"
3. Verify behavior matches expectations
4. Only then modify the actual file

Database Work

1. START: mcp__tidewave__get_ecto_schemas - Understand data models
2. EXPLORE: mcp__tidewave__execute_sql_query - Inspect actual data
3. TEST: mcp__tidewave__project_eval - Test Ecto queries
4. IMPLEMENT: Make schema/migration changes

Debugging Issues

1. CHECK: mcp__tidewave__get_logs - Recent errors
2. LOCATE: mcp__tidewave__get_source_location - Find problem code
3. TEST: mcp__tidewave__project_eval - Reproduce issue
4. FIX: Edit the file with the solution

IEx Helpers Available in project_eval

• h(Module) - Get help for a module
• exports(Module) - List all exported functions
• i(value) - Inspect data structure info
• t(Module) - Show types defined in module
• b(Module) - Show behaviours module implements
• arguments - Access passed arguments array

Database Query Gotchas

When using execute_sql_query:

• UUIDs return as 16-byte binaries - cast with ::text (PostgreSQL)
• Results limited to 50 rows - use LIMIT/OFFSET for pagination
• Use parameterized queries: query: "SELECT * FROM users WHERE id = $1", arguments: [123]

Common Mistakes to Avoid

❌ DON'T:

• Use bash to run mix commands for code evaluation
• Use grep to find module definitions when you know the module name
• Read entire files to find function documentation
• Run iex in bash instead of using project_eval
• Search file system for Ecto schemas before using get_ecto_schemas

✅ DO:

• Use project_eval for ALL Elixir code execution
• Use get_source_location for known modules
• Use get_docs for documentation
• Use get_ecto_schemas first for schema discovery
• Use Tidewave MCP tools as your primary interface

Remember: Tidewave Is Your Superpower

The Tidewave MCP server gives you:

• Direct access to the running Elixir application
• Instant code evaluation with full project context
• Database introspection without external tools
• Documentation at your fingertips
• Source navigation faster than file search

Every time you reach for Bash, Grep, or Read for Elixir code, ask yourself: "Can Tidewave MCP do this better?" The answer is almost always YES.