OPNSense MCP Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries full burden. It only states the action ('find') without disclosing behavioral traits like whether this is a read-only query, what data is returned, if it requires authentication, or potential errors (e.g., invalid MAC format). For a tool with no annotations, this is insufficient transparency.

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?

The description is a single, efficient sentence with no wasted words. It's front-loaded and directly states the tool's purpose, making it easy to parse. This is an example of optimal conciseness for a simple tool.

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?

Given no annotations and no output schema, the description is incomplete. It doesn't explain what 'find' entails (e.g., returns device details, status, or location), error conditions, or usage context relative to siblings. For a tool with minimal structured data, the description should provide more operational context.

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?

The input schema has 100% description coverage, with the 'mac' parameter documented as 'MAC address (with or without colons)'. The description adds no additional meaning beyond this, as it merely restates the parameter's purpose. With high schema coverage, the baseline score of 3 is appropriate.

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?

The description 'Find device by MAC address' clearly states the action (find) and resource (device), but it's vague about what 'find' means (retrieve details? locate on network?) and doesn't distinguish from sibling tools like 'find_device_by_name' or 'find_arp_by_mac'. It's functional but lacks specificity about the exact operation.

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 guidance is provided on when to use this tool versus alternatives. With siblings like 'find_device_by_name' and 'find_arp_by_mac', the description doesn't explain if this is for device lookup versus ARP resolution, or when MAC-based search is preferred over other methods. This leaves the agent without context for tool selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.