OPNSense MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool's function but doesn't describe what the output looks like (e.g., list of entries, error handling), whether it's read-only or has side effects, performance characteristics, or any constraints like rate limits. For a tool with zero annotation coverage, this is a significant gap in 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 that directly states the tool's purpose without unnecessary words. It's front-loaded with the core functionality and avoids redundancy. Every part of the sentence earns its place by specifying the action, resource, and filter criterion.

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 the lack of annotations and output schema, the description is incomplete. It doesn't explain what ARP entries are, the return format (e.g., structured data, error messages), or behavioral aspects like whether it's a safe read operation. For a tool with no structured metadata, the description should provide more context to compensate, but it remains minimal.

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 'macPattern' clearly documented as accepting MAC addresses or partial MACs with or without colons. The description adds no additional parameter semantics beyond what's in the schema, such as format examples or search behavior details. 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 clearly states the action ('Find') and resource ('ARP entries') with the specific filter criterion ('by MAC address'). It distinguishes from siblings like 'find_arp_by_hostname' and 'find_arp_by_ip' by specifying the MAC-based lookup. However, it doesn't explicitly mention what ARP entries are or the scope of the search.

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. It doesn't mention sibling tools like 'find_device_by_mac' for broader device searches or 'list_arp_entries' for unfiltered listings. The description implies usage for MAC-based ARP lookups but offers no context on prerequisites, limitations, or comparison to other tools.

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