Creates or updates the DECISIONS.md file in .project/ directory. Use this when documenting architecture decisions, trade-offs, or rationale. Helps maintain a decision log for the project.
AI agents use create_or_update_decisions to create or update resources in Project MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Project MCP environment.
The tool creates or updates a documentation file (DECISIONS.md), which is a Write operation—it modifies project state reversibly. While documentation changes could theoretically impact project direction, the blast radius is limited to altering decision records rather than executing code, deleting data, or affecting financial systems.
From the tool's definition Tool name contains 'create_or_update' which modifies data; description states it 'Creates or updates the DECISIONS.md file' in the project directory. This is reversible data creation/modification.
Documented attack patterns abuse exactly the kind of access create_or_update_decisions gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Project MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for create_or_update_decisions:
{
"version": "1",
"default": "deny",
"tools": {
"create_or_update_decisions": {
"limits": [
{
"counter": "create_or_update_decisions_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_or_update_decisions stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Creates or updates the DECISIONS.md file in .project/ directory. Use this when documenting architecture decisions, trade-offs, or rationale. Helps maintain a decision log for the project. It is categorised as a Write tool in the Project MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Project MCP server in PolicyLayer and add a rule for create_or_update_decisions: 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 Project MCP. Nothing to install.
create_or_update_decisions is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the create_or_update_decisions 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 create_or_update_decisions. 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.
create_or_update_decisions is provided by the Project MCP server (pouyanafisi/project-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Project MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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42 Project MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.