Replaces a Hetzner Cloud firewall's existing rules with the provided rule set; pass an empty array to remove all rules.
Set Rules
Set the rules of a Firewall.
Overwrites the existing rules with the given ones. Pass an empty array to remove all rules.
Rules are limited to 50 entries per Firewall and 500 effective rules.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | ID of the Firewall. | |
| body | Yes |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true and readOnlyHint=false, so safety is covered structurally; the description adds the critical nuance that ALL existing rules are replaced and that an empty array wipes the rule set, plus hard limits (50 rules / 500 effective). It does not disclose async/action-return behavior or permission requirements, keeping it short of a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Four short sentences, front-loaded with the action itself and immediately followed by the destructive overwrite semantics. The final limits sentence is partially redundant with the `rules` schema description, which is the only waste.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a destructive, nested-body mutation with no output schema, the description covers replacement semantics and limits but leaves out operational context an agent would want: that this returns an async action, that rules are enforced on attached servers, and that the firewall must already exist. Adequate but with clear gaps.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage sits at 50%, but the nested `rules` schema is richly self-documented (protocol enums, source_ips vs destination_ips, CIDR notes). The description only adds the empty-array semantics and the count limits, so it is the minimum-viable complement rather than a compensator.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource: 'Set the rules of a Firewall', with a note on overwrite semantics. An agent can distinguish this from hcloud_update_firewall (metadata edits) by the wording, but no sibling is named explicitly, so differentiation is inferred rather than stated.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description says the existing rules are overwritten and that an empty array clears all rules, which is essential usage context, but it never states when to prefer this over hcloud_update_firewall or when it is inappropriate (e.g. firewalls already applied to servers). Usage is implied rather than guided.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.