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. 'Find ARP entries' suggests a read-only query, but it doesn't disclose important behavioral aspects: whether this requires specific permissions, what format the results take (e.g., list of entries with what fields), whether it's real-time or cached data, or any rate limits. The description is minimal and lacks operational context.

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 extremely concise at just 6 words, front-loading the essential information ('Find ARP entries on specific interface') with zero wasted words. Every element earns its place, making it immediately scannable and understandable.

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 insufficiently complete. For a network diagnostic tool querying ARP tables, users need to know what information is returned (MAC addresses, IPs, timestamps), whether results are filtered or complete, and any system-specific behaviors. The minimal description leaves too many operational questions unanswered.

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 description coverage is 100% with the single 'interface' parameter fully documented in the schema. The description adds no additional parameter semantics beyond what's already in the schema (interface name examples). With complete schema coverage, the baseline score of 3 is appropriate as the description doesn't enhance parameter understanding.

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 ARP entries') and the target resource ('on specific interface'), making the purpose immediately understandable. However, it doesn't explicitly differentiate from its siblings like 'find_arp_by_hostname', 'find_arp_by_ip', 'find_arp_by_mac', or 'list_arp_entries', which all query ARP data differently.

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 provides no guidance on when to use this tool versus alternatives. With multiple ARP-related siblings (find_arp_by_hostname, find_arp_by_ip, find_arp_by_mac, list_arp_entries), there's no indication of when interface-based lookup is preferred over other methods or what distinguishes this from 'list_arp_entries' which might return all entries.

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