symbi-verify

symbi-verify is a skill for Claude Code, Codex from ThirdKeyAI/symbi-gemini-cli. It costs 33 tokens per session (259 once invoked), scanned A, original, Apache-2.0.

A guide for checking whether MCP tool descriptions have been cryptographically altered. MCP is a standard way for coding agents to connect to external tools.

In plain words
What is it for?
Use it when adding or updating MCP servers, auditing integrations, investigating unexpected tool results, or checking a schema's verification status.
Why use it?
It helps identify changed, untrusted, or unsigned tool schemas before the agent uses them.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Gemini CLI.

Good fit Use it when adding or updating MCP servers, auditing integrations, investigating unexpected tool results, or checking a schema's verification status.

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Install with agentmods
npx agentmods add skills/thirdkeyai/symbi-gemini-cli/symbi-verify
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add ThirdKeyAI/symbi-gemini-cli --skill symbi-verify
Clone the repo
git clone --depth 1 https://github.com/ThirdKeyAI/symbi-gemini-cli

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for symbi-verify

README.md
[![agentmods](https://agentmods.dev/badge/skills/thirdkeyai/symbi-gemini-cli/symbi-verify.svg)](https://agentmods.dev/skills/thirdkeyai/symbi-gemini-cli/symbi-verify)
Your own site
<a href="https://agentmods.dev/skills/thirdkeyai/symbi-gemini-cli/symbi-verify"><img src="https://agentmods.dev/badge/skills/thirdkeyai/symbi-gemini-cli/symbi-verify.svg" alt="Measured on agentmods" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 259 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00033 $0.00259
Opus 5 $0.00016 $0.00130
Sonnet 5 $0.00007 $0.00052
Haiku 4.5 $0.00003 $0.00026

Measured 7d ago against content hash 2bfecac3c32f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

symbi-verify scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/symbi-verify/SKILL.md · 31 lines

What it actually says

SchemaPin Verification

Verify the cryptographic integrity of MCP tool schemas to ensure they haven't been tampered with.

Verification Process

  1. Identify the MCP server to verify (from the extension manifest or the user's request)
  2. Use the symbi__verify_schema tool to check the schema
  3. Report the verification result:
    • Verified: Schema signature matches the publisher's key
    • TOFU: First-time use, key has been pinned for future verification
    • Failed: Schema has been modified since signing -- DO NOT USE
    • No signature: Schema is unsigned -- warn the user about risks

When to Verify

  • Before first use of any new MCP tool
  • After updating MCP server configurations
  • When security audit is requested
  • When a tool returns unexpected results

Note on Tool Names

In Gemini CLI, MCP tools are prefixed with the server alias and double underscore. The symbi MCP tools are accessed as symbi__verify_schema, symbi__list_agents, etc.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 31 lines · 33 tokens per session scan A 2bfecac3c32f

Subscribe to this mod's changes

symbi-verify is a skill published in the GitHub repository ThirdKeyAI/symbi-gemini-cli (3 stars, last pushed 6mo ago), licensed Apache-2.0. It adds 33 tokens to every session and 259 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.