AI agents use send_estimate_message to create or update resources in Harvest MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Harvest MCP Server environment.
The tool name suggests sending a message (a Write action), and in the context of a time-tracking/billing system with estimates, this would transmit information about an estimate to clients or stakeholders. This is reversible (messages can be unsent or recalled in some systems, or simply represent a communication action), so it maps to Write rather than Execute.
From the tool's definition Tool name 'send_estimate_message' indicates it sends/transmits a message associated with an estimate. Combined with sibling tools that create and manage estimates (create_estimate, get_estimate_details), this tool likely writes or transmits data to clients or…
Documented attack patterns abuse exactly the kind of access send_estimate_message gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Harvest MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for send_estimate_message:
{
"version": "1",
"default": "deny",
"tools": {
"send_estimate_message": {
"limits": [
{
"counter": "send_estimate_message_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}send_estimate_message 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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send_estimate_message. It is categorised as a Write tool in the Harvest MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Harvest MCP Server MCP server in PolicyLayer and add a rule for send_estimate_message: 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 Harvest MCP Server. Nothing to install.
send_estimate_message 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 send_estimate_message 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 send_estimate_message. 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.
send_estimate_message is provided by the Harvest MCP Server MCP server (taiste/harvest-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 21 Harvest MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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21 Harvest MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.