StackBridge
Parses Axios HTTP calls in frontend code to link them to backend API routes, enabling cross-stack dependency analysis.
Analyzes FastAPI route definitions, parameters, and response models to detect breakages when frontend or database changes.
Traces fetch calls in Next.js applications to map frontend components to backend API routes and database models.
Parses Pydantic models to verify API contract consistency across the full stack.
Analyzes React component ASTs to identify dependencies on API routes and database models.
Parses React Query usage to link data fetching logic to backend endpoints and detect breaking changes.
Traces SQLAlchemy ORM models to understand database schema changes and their impact on API routes and frontend code.
π StackBridge-MCP
Sub-1ms Cross-Stack AST Contract & Verification Layer for AI Coding Agents
π‘ Why StackBridge?
When AI coding agents (Cursor, Claude Code, Windsurf, Antigravity) edit backend models or API routes in full-stack codebases, backend unit tests frequently pass while the frontend silently breaks in production:
An agent modifies an API parameter or Pydantic/SQLAlchemy field in
backend/routes.py.Backend tests pass in isolation. Nothing warns the agent.
The React/Next.js client calling that endpoint across the boundary fails with runtime errors.
StackBridge-MCP is an always-warm Model Context Protocol (MCP) server that parses full-stack AST relationships, discovers cross-stack blast radii in 0.75 ms, and verifies changes using baseline-diffed compiler checks with zero false positives.
React / Next.js Client FastAPI Routes SQLAlchemy ORM Models
(TypeScript AST) ββββΊ (Python AST) ββββΊ (Schema AST)
UserProfile.tsx get_user_billing() BillingAccountRelated MCP server: Stratum MCP Server
β‘ Key Highlights
π² Tree-sitter AST Graph: Parses Next.js (
fetch, Axios, React Query) β FastAPI routes β SQLAlchemy ORM models without heavy LSP sidecars or runtime imports.β‘ Sub-1ms Traversal: Persistent SQLite WAL database with recursive Common Table Expressions (0.75 ms traversal query latency).
π 99.74% Prompt Token Reduction: Replaces massive multi-file code dumps with compact, mathematically precise AST contract slices.
π‘οΈ Root-Cause Diagnostic Ranking: Graph-distance BFS ranks errors (
π΄ PRIMARY ROOT CAUSEvsβ οΈ CASCADING BREAKAGE) and outputs immediate Git diff patches.π§ͺ Test Impact Selection: Isolates test suites impacted by a schema change and highlights untested blast-radius paths (0% coverage).
π Interactive Canvas: Built-in localhost tripartite visualizer (
stackbridge ui) onhttp://127.0.0.1:3456.π Continuous Intelligence: Background file watcher daemon (
stackbridge watch) and livingAGENTS.mdcontext generator.
π Real-World Benchmarks
Empirical performance measured on fastapi-realworld-example-app (44 files, 23 AST dependency nodes, 10 cross-boundary edges):
Benchmark Metric | Raw Codebase Dump | StackBridge Compact Slice | Improvement / Latency |
Context Window Size |
|
| π 99.74% Token Reduction |
Blast Radius Traversal | Full-repo search: | SQLite Recursive CTE: | β‘ 200x Faster Traversal |
Compiler Verification | Global linter: | Baseline-Diffed Engine: | π‘οΈ Zero False Positives |
Automated Test Suite | β | 56 / 56 tests passing | β 100% Passing |
See full benchmark methodology in docs/benchmarks.md and REAL_WORLD_BENCHMARK.md.
π Quick Start
Option 1: Zero-Install Execution (Recommended via uvx)
uvx stackbridge serveOption 2: Pip Installation
pip install stackbridge
stackbridge serveβοΈ Client Configuration
Connect StackBridge to your AI pair programmer over standard JSON-RPC 2.0 stdio:
1. Cursor (.cursor/mcp.json)
{
"mcpServers": {
"stackbridge": {
"command": "uvx",
"args": ["stackbridge", "serve"]
}
}
}2. Claude Desktop (claude_desktop_config.json)
{
"mcpServers": {
"stackbridge": {
"command": "python",
"args": ["-m", "stackbridge.main", "serve", "--transport", "stdio"]
}
}
}π€ MCP Tools Reference
StackBridge exposes high-ergonomics tools to coding agents:
Tool Name | Arguments | Description |
|
| Traces the full-stack dependency chain: Frontend component β API route β Database model. |
|
| Extracts HTTP methods, status codes, response models, and linked frontend fetch callers with confidence scores. |
|
| Runs in-memory compiler checks across impacted files, ranking root causes and proposing diff patches. |
|
| Returns real-time full-stack boundary stats, node counts, edge counts, and breakage drift status. |
π» CLI Reference
# Index a repository and export the dependency graph
stackbridge index --repo-path . --force
# Trace blast radius for a model or route
stackbridge trace --target BillingAccount
# Run pre-commit boundary verification guard
stackbridge guard --fail-on-error
# Launch interactive tripartite web visualizer
stackbridge ui --port 3456
# Start continuous background watcher daemon
stackbridge watch
# Generate living AGENTS.md boundary architecture guide
stackbridge init-agents
# Execute performance and token reduction benchmarks
stackbridge benchmark --runs 3 --output BENCHMARK.mdπ Repository Structure
StackBridge-MCP/
βββ .github/
β βββ workflows/ci.yml # CI pipeline (Python 3.10-3.13 on Ubuntu/Windows/macOS)
β βββ ISSUE_TEMPLATE/ # Bug report and feature request issue templates
β βββ PULL_REQUEST_TEMPLATE.md # Standard PR checklist
βββ docs/
β βββ architecture.md # Subsystem breakdown and Mermaid diagrams
β βββ benchmarks.md # Benchmark methodology and raw metrics
β βββ ast_extraction_spec.md # Tree-sitter extractor grammar specifications
βββ stackbridge/
β βββ core/ # Unified StackGraph, SQLite CTE store, watcher, route matcher
β βββ parsers/ # Tree-sitter parsers (TS fetch, Python routes, SQLAlchemy)
β βββ verifier/ # Baseline-diffed verifier, root-cause ranker, test impact selector
β βββ mcp_server/ # FastMCP stdio server and JSON-RPC tools
β βββ benchmarks/ # Benchmark runner and markdown report generator
β βββ ui/ # Localhost tripartite interactive canvas
βββ tests/ # 56 automated test suites (parsers, verifiers, MCP E2E, CTE)
βββ AGENTS.md # Living agent architecture guide
βββ CHANGELOG.md # Version release notes
βββ CONTRIBUTING.md # Contribution and development guidelines
βββ LICENSE # MIT License
βββ pyproject.toml # Package metadata and tool configurationsπ License
This project is licensed under the MIT License.
Available Tools
5 toolsget_route_contractB
Extracts the API contract for a route, including HTTP method, status codes, response model, and all linked frontend fetch callers with confidence scores.
| Name | Required | Description | Default |
|---|---|---|---|
| repo_path | No | . | |
| route_path | Yes |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description carries the transparency burden. It discloses the output contents and implies a read-only extraction operation, but it does not mention edge cases, external dependencies, or any side effects beyond the output.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single focused sentence that front-loads the primary action and lists the key output categories without any wasted words. It is appropriately concise and scannable.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description names the main outputs and an output schema exists, but parameter semantics are severely under-documented (0% schema coverage). The tool needs at least a brief note on how route_path should be specified and what repo_path controls to be fully actionable.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, and the description provides no parameter-level meaning. It does not explain the expected format of route_path or the purpose of repo_path, leaving both parameters semantically under-specified.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb 'Extracts' and identifies the resource as 'API contract for a route'. It lists concrete deliverables (HTTP method, status codes, response model, callers with confidence scores), which clearly distinguishes it from sibling tools like trace_fullstack_path and get_stack_health.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies the tool should be used when one needs a route's API contract, but it does not explicitly state when to use it versus alternatives. No exclusions or contrast with sibling tools are provided, leaving some selection inference to the agent.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_stack_healthC
Returns stack health diagnostics, graph statistics, and verification metrics.
| Name | Required | Description | Default |
|---|---|---|---|
| repo_path | No |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description bears full responsibility for behavioral transparency. It does not disclose any side effects, access requirements, performance implications, or what 'health diagnostics' entails (e.g., whether it mutates state or is read-only).
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, concise sentence that lists the types of results. It is front-loaded and efficient, though it could be improved by adding brief usage context without sacrificing brevity.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the presence of an output schema and the complexity of a diagnostic tool, the description lacks sufficient context. It does not explain the tool's role relative to siblings, what 'stack health' includes, or how to interpret the results beyond what the output schema provides.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, and the description does not explain the purpose or default behavior of the 'repo_path' parameter. The schema shows it is optional with a null default, but without context, the agent cannot infer what happens when it is omitted or provided.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states what the tool does (returns diagnostics, statistics, metrics), but it is vague about the specific resource or domain. 'Stack health' is not clearly defined, and the description does not distinguish this tool from siblings like 'trace_fullstack_path' or 'verify_breakage'.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided on when to use this tool versus its siblings. For example, it does not clarify whether this is a general health check or a debugging step, and no exclusions or prerequisites are mentioned.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
trace_fullstack_pathB
Traces fullstack dependency chain across Frontend, API Routes, and SQLAlchemy ORM models.
Returns the complete path: Frontend component -> API Route handler -> Database Model.
| Name | Required | Description | Default |
|---|---|---|---|
| target | No | ||
| repo_path | No | ||
| symbol_or_path | No |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must fully disclose behavioral traits. It explains what the tool returns but does not mention whether it modifies state, requires authentication, handles large repos, or what happens if targets are not found.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is concise and front-loaded with the core purpose. Every sentence adds value without repetition or unnecessary detail.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers the basic return structure but lacks guidance on parameter usage, error handling, or performance implications. Given the complexity of tracing fullstack dependencies and having zero annotation coverage, more detail is needed to be complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, so the description should clarify parameter meanings. The description mentions a 'target' concept but does not explain the roles of target, repo_path, or symbol_or_path, nor how they interact. With multiple optional parameters, the semantics are ambiguous.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool traces a fullstack dependency chain across Frontend, API Routes, and SQLAlchemy ORM models, specifying the resources involved and the return path format. This distinguishes it well from siblings like get_route_contract or get_stack_health.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided on when to use this tool versus alternatives such as get_route_contract or verify_schema_change. The description does not indicate what input is needed or prerequisites like a valid repo path.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
verify_breakageA
Runs compiler and schema verification across all files impacted by a change.
| Name | Required | Description | Default |
|---|---|---|---|
| repo_path | No | . | |
| modified_files | No |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden. It explains what the tool does (runs compiler and schema verification) and the scope (across all files impacted by a change), but it does not disclose behavioral traits such as whether it modifies files, requires specific permissions, has side effects, or what the output schema represents. This is adequate but not exceptional.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, clear sentence that efficiently conveys the tool's purpose without unnecessary words. It is front-loaded and earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool has two optional parameters and an output schema, the description provides a solid overview of the tool's function. It could benefit from noting that both parameters are optional, but the context signals help there. The description is complete enough for an agent to understand the tool's core purpose and scope.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, so the description must compensate for the two parameters. It does not explain the meaning of 'repo_path' or 'modified_files' beyond their names in the schema. However, the description of the tool's action (running verification across impacted files) gives implicit context that 'modified_files' likely lists changed files and 'repo_path' is the repository root. This is minimal value added.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the verb 'Runs' and the resource 'compiler and schema verification across all files impacted by a change', which is specific and distinguishes it from siblings like 'verify_schema_change' (which focuses only on schema) and 'get_stack_health' (which checks overall health).
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies usage when a change has been made and needs verification, but it does not explicitly state when to use this tool versus alternatives like 'verify_schema_change' or 'trace_fullstack_path', nor does it mention when not to use it or any prerequisites.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
verify_schema_changeC
Runs compiler and schema verification across all files impacted by a change.
| Name | Required | Description | Default |
|---|---|---|---|
| repo_path | No | . | |
| modified_files | No | ||
| schema_changes | No |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of disclosing behavioral traits. The description does not mention what happens upon failure (e.g., error messages, warnings), whether the tool modifies any state, or if it requires network access or specific permissions. The behavior is presented too abstractly for safe agent invocation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single sentence of 10 words, which is concise. It front-loads the key verbs (runs compiler and schema verification). However, it omits essential details, crossing the line from concise to underspecified. Still, brevity is maintained.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given zero annotations, no output schema explanation (but an output schema exists), and 3 parameters with no description, the tool description fails to provide enough context. The agent needs to know the output format (what success/failure looks like), the expected data format for parameters, and how this relates to sibling tools. The description is incomplete for a tool of moderate complexity.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema has 3 parameters with 0% description coverage, meaning the schema itself provides no descriptions. The tool description does not clarify the parameters eitherβ'repo_path', 'modified_files', and 'schema_changes' are not explained in terms of format or semantics. Since there are no enums, the agent cannot guess valid values. A score of 3 is generous because the schema's structure hints at purpose, but the lack of any explanation makes selection difficult.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states the tool runs compiler and schema verification across impacted files, which gives a clear verb+resource combination. However, it does not distinguish this tool from its siblings like 'verify_breakage' or 'trace_fullstack_path', which might have overlapping purposes. The purpose is adequate but lacks differentiation.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
There is no guidance on when to use this tool versus alternatives like 'verify_breakage' or 'get_route_contract'. The description does not indicate prerequisites, such as needing a git diff or pre-identified list of modified files. Without any usage context, an AI agent may misuse or underuse the tool.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections. Dates show when Glama detected each change.
5 tool updates
v0.1.0- First observed
get_route_contract - First observed
get_stack_health - First observed
trace_fullstack_path - First observed
verify_breakage - First observed
verify_schema_change
TDQS
Two tools (verify_schema_change and verify_breakage) have identical descriptions, making them indistinguishable. Other tools are distinct but the duplication severely harms disambiguation.
All tools follow a consistent snake_case verb_noun pattern (trace_, get_, verify_, get_). No mixing of conventions.
Five tools is a well-scoped, focused set for a StackBridge server that handles dependency tracing, contract extraction, verification, and health diagnostics.
Core analysis features are present, but the duplicate verify tools indicate poor domain modeling. Missing a tool to list all routes or contracts, and it's unclear if schema verification and breakage verification are truly separate concepts.
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