Modify an existing Tally form
AI agents use modify_form to create or update resources in Tally MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Tally MCP environment.
The tool creates or modifies data (forms) in a reversible manner without deleting or destroying information. It does not execute arbitrary code, move money, or permanently remove data. The severity is medium because modifications to forms could affect form functionality, data collection, or user experience, but the action is reversible via subsequent modifications or restoration from backups.
From the tool's definition Tool description states 'Modify an existing Tally form', and the broader server description emphasizes 'update...forms using natural language'. Modifying forms is a reversible data mutation operation.
Documented attack patterns abuse exactly the kind of access modify_form gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Tally MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for modify_form:
{
"version": "1",
"default": "deny",
"tools": {
"modify_form": {
"limits": [
{
"counter": "modify_form_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}modify_form 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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Modify an existing Tally form. It is categorised as a Write tool in the Tally MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Tally MCP server in PolicyLayer and add a rule for modify_form: 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 Tally MCP. Nothing to install.
modify_form 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 modify_form 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 modify_form. 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.
modify_form is provided by the Tally MCP server (learnwithcc/tally-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Tally 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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18 Tally MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.