# signature_search

Use when the agent already knows the signature shape it wants — e.g. fn(&str) -> Result<Vec<u8>, _>, fn(&[u8]) -> Result<String, std::str::Utf8Error>, or impl Iterator<Item=Result<...>>. Returns ranked candidate functions with the crate they live in, downloads, yank status, and a compact behavior summary if probed. Pass the exact signature verbatim; the substrate normalises whitespace + identifiers on its end.

Agent View of the PolicyLayer registry record for `signature_search`. HTML page: https://policylayer.com/tools/dev-codeitall-codeitall/signature-search

## Facts

- Tool: `signature_search`
- Server: Codeitall (`https://api.codeitall.dev/mcp`) — https://policylayer.com/tools/dev-codeitall-codeitall.md
- Homepage: https://github.com/codeitalldev/codeitall
- Risk category: Read (Low risk)
- Registry record: grade B, identity unverified
- Server rate-limited: no
- Parameters: 3 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `shape` | string | yes |  |
| `top_n` | integer | no |  |
| `language` | string | no |  |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "signature_search",
    "arguments": {
      "shape": "<shape>"
    }
  }
}
```

## Why signature_search is rated Low

This is a search and query operation that retrieves read-only information from a knowledge base of Rust crate APIs. It takes a function signature as input and returns matching candidates with metadata. There are no side effects, mutations, or irreversible actions. The blast radius of misuse is minimal since it only exposes existing public API information.

From the tool's own definition: "The tool description states it 'Returns ranked candidate functions' and retrieves information like 'crate they live in, downloads, yank status, and behavior summary'."

## Use case

AI agents call signature_search to retrieve information from Codeitall without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Codeitall:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "signature_search": {}
  }
}
```

## Other tools on Codeitall (7)

- `answer_api_question` — Read — https://policylayer.com/tools/dev-codeitall-codeitall/answer-api-question.md
- `behavior_lookup` — Read — https://policylayer.com/tools/dev-codeitall-codeitall/behavior-lookup.md
- `compare_implementations` — Read — https://policylayer.com/tools/dev-codeitall-codeitall/compare-implementations.md
- `find_modern_equivalent` — Read — https://policylayer.com/tools/dev-codeitall-codeitall/find-modern-equivalent.md
- `list_families` — Read — https://policylayer.com/tools/dev-codeitall-codeitall/list-families.md
- `package_trust` — Read — https://policylayer.com/tools/dev-codeitall-codeitall/package-trust.md
- `pattern_consensus` — Read — https://policylayer.com/tools/dev-codeitall-codeitall/pattern-consensus.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=dev-codeitall-codeitall · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/dev-codeitall-codeitall