Adds a new prompt to the project-specific prompt directory.
AI agents use add_prompt to create or update resources in Prompt Registry MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Prompt Registry MCP environment.
The add_prompt tool creates new prompt entries in a file-based storage system. This is a Write operation because it creates data with no destructive or side effects beyond storage. Severity is low because prompts are configuration/template data with limited blast radius if added incorrectly—they can be updated or deleted. Confidence is high given the clear, explicit description of its purpose.
From the tool's definition Tool description states it 'Adds a new prompt to the project-specific prompt directory.' This is a create operation that stores new data reversibly.
Documented attack patterns abuse exactly the kind of access add_prompt gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Prompt Registry MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for add_prompt:
{
"version": "1",
"default": "deny",
"tools": {
"add_prompt": {
"limits": [
{
"counter": "add_prompt_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_prompt 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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Adds a new prompt to the project-specific prompt directory. It is categorised as a Write tool in the Prompt Registry MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Prompt Registry MCP server in PolicyLayer and add a rule for add_prompt: 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 Prompt Registry MCP. Nothing to install.
add_prompt 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 add_prompt 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 add_prompt. 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.
add_prompt is provided by the Prompt Registry MCP server (stevengonsalvez/promptregistry-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Prompt Registry 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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7 Prompt Registry MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.