aspex mcp

claude mcp add aspex -- aspex-scan mcp --no-exec

{ "mcpServers": { "aspex": { "command": "aspex-scan", "args": ["mcp", "--no-exec"] } } }

aspex-scan mcp serves Aspex over the Model Context Protocol on stdin/stdout. The point is a workflow like this:

Agent:  I want to add a filesystem server with access to /.
        → aspex_security_impact({ mcp_json: <proposed .mcp.json> })

Aspex:  verdict: introduces a CRITICAL attack path
        blast_radius_before: MEDIUM  blast_radius_after: HIGH
        attack_paths_added: [AP001 filesystem + browser: sensitive data exfiltration, ...]
        changes: FILESYSTEM SCOPE EXPANDED, credential directories newly reachable, ...

Aspex does not block the edit. It makes the consequence visible before the edit, to the thing about to make it.

Tools

Tool	Returns
`aspex_security_impact`	drift between the current environment and a proposed `.mcp.json` (plus optional `.claude/settings.json` hooks): verdict, blast radius before/after, security-relevant changes, attack paths added and removed. The proposal is analyzed statically and never launched. Existing user-level servers are included so compositions with them are visible.
`aspex_explain`	the deterministic answer to a security question (see explain)
`aspex_scan`	agents, servers with capabilities and scope, hook and skill counts, blast radius with reasons, attack path counts
`aspex_get_capabilities`	every server’s capabilities, roots, scope, egress class, agent-state writes
`aspex_get_attack_paths`	AP001-AP006 with evidence, impact, remediation
`aspex_verify`	drift against a lockfile (`.lock` or `.json` paths only)

Read-only by construction

There are no write, exec, fix or configuration tools. The server cannot modify files, run commands, or change Aspex’s own policy, lockfile or baseline. aspex_verify reads only lockfiles. The environment is computed once per process and cached; restart the server to rescan. The tool list is fixed in code and covered by a test that fails if a tool name ever looks like a write or exec action.

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Tools

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​Tools

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Tools

Read-only by construction