Look up a class, function, method, or variable definition from the index when repository readiness is ready. If the tool returns index_unavailable with safe_fallback=native_search, use native search and follow the readiness remediation, such as reindex. Ready misses return not_found with readines...
AI agents call symbol_lookup to retrieve information from Code-Index-MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only retrieves symbol definitions from an indexed codebase. It performs queries and lookups without modifying, executing, or deleting anything. The path validation (filesystem_paths must be inside MCP_ALLOWED_ROOTS) is a safety boundary, not a capability elevation.
From the tool's definition Tool description states it 'Look[s] up a class, function, method, or variable definition from the index' and 'returns index_unavailable' or 'not_found' — pure retrieval operations with no side effects.
Documented attack patterns abuse exactly the kind of access symbol_lookup gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Code-Index-MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for symbol_lookup:
{
"version": "1",
"default": "deny",
"tools": {
"symbol_lookup": {}
}
}symbol_lookup is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Look up a class, function, method, or variable definition from the index when repository readiness is ready. If the tool returns index_unavailable with safe_fallback=native_search, use native search and follow the readiness remediation, such as reindex. Ready misses return not_found with readiness metadata. Accepts optional repository param (registered repo name or filesystem path); filesystem paths must be inside MCP_ALLOWED_ROOTS or the tool returns path_outside_allowed_roots. It is categorised as a Read tool in the Code-Index-MCP MCP Server, which means it retrieves data without modifying state.
Register the Code-Index- MCP server in PolicyLayer and add a rule for symbol_lookup: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Code-Index-MCP. Nothing to install.
symbol_lookup is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the symbol_lookup rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for symbol_lookup. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
symbol_lookup is provided by the Code-Index- MCP server (viperjuice/code-index-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 8 Code-Index-MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
8 Code-Index-MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.