concurrency-mutex
A mutex tool (maxConcurrent: 1, no queue)
This record as markdown: /tools/frontmcp/concurrency-mutex.md
What concurrency-mutex does on Frontmcp
AI agents invoke concurrency-mutex to trigger actions in Frontmcp. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
Why concurrency-mutex is rated High
A mutex tool controls concurrent execution by limiting simultaneous access to 1. This is an execution-control primitive that can block or gate other operations. The description is minimal, lowering confidence, but the nature of a mutex is to manage execution flow rather than read, write, or destroy data. Severity is medium because misuse could cause deadlocks or denial-of-service by blocking concurrent operations.
From the tool's definition 'A mutex tool (maxConcurrent: 1, no queue)' — describes a concurrency control mechanism that executes with a mutual exclusion lock
Attacks that exploit this kind of access
The rule that runs concurrency-mutex safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Frontmcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For concurrency-mutex, this is the rule to start with:
concurrency-mutex stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Frontmcp, apply this rule, and every concurrency-mutex call is checked against it from then on.
Questions about concurrency-mutex
A mutex tool (maxConcurrent: 1, no queue). It is categorised as a Execute tool in the Frontmcp MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Front MCP server in PolicyLayer and add a rule for concurrency-mutex: 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 Frontmcp. Nothing to install.
concurrency-mutex is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the concurrency-mutex 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 concurrency-mutex. 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.
concurrency-mutex is provided by the Front MCP server (agentfront/frontmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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