Attach a firewall to a Hetzner Cloud server by firewall ID or name, enforcing its rules on that server via the API apply-to-resources action.
Apply a firewall (by id or by name) to a server. Hand-tuned wrapper around POST /firewalls/{id}/actions/apply_to_resources.
| Name | Required | Description | Default |
|---|---|---|---|
| server_id | Yes | ||
| firewall_id | No | ||
| firewall_name | No |
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 openWorldHint=true, so the safety profile is covered. The description adds that it hits POST /firewalls/{id}/actions/apply_to_resources and that the firewall may be selected by id or name, but it never says what the mutation actually does to existing firewall assignment on the server (replace vs. append) or what permissions are needed.
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?
Two short sentences, no filler, and the core action is front-loaded before the implementation note. Nothing here could be cut without losing information.
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 3-parameter mutation with no output schema and a sibling that overlaps almost entirely, the description is thin: it omits replacement semantics, the id/name mutual-exclusivity rule, and why to pick this over hcloud_firewall_apply_to_resources_action. The endpoint reference is useful but is implementation trivia rather than agent-facing guidance.
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 is 0%, so the description must compensate, and it partially does by clarifying the id-vs-name selector for the firewall. It does not clarify that server_id and the firewall selector are separate concerns, nor whether firewall_id and firewall_name are mutually exclusive or which wins if both are supplied.
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 ("Apply a firewall ... to a server") and even names the underlying API endpoint. It does not differentiate from the sibling hcloud_firewall_apply_to_resources_action, which performs the same POST against arbitrary resources, so an agent has to infer the scoping difference.
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?
No when-to-use guidance, no prerequisites, no exclusions. The presence of hcloud_firewall_apply_to_resources_action (a near-identical sibling) makes the missing routing guidance a real gap — nothing says to prefer this one when targeting a single server.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.