OPNSense MCP Server

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

With no annotations provided, the description carries full burden but only states what it does, not how it behaves. It doesn't disclose whether this is a read-only operation, if it requires authentication, rate limits, pagination, return format, or error conditions. 'Get all' suggests a list operation, but behavioral details are missing.

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 front-loads the core purpose. Every word earns its place: 'Get' (action), 'all devices' (resource scope), 'on guest network' (context), '(VLAN 4)' (specific detail). No wasted words or redundancy.

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 tool's simplicity (0 parameters, no annotations, no output schema), the description is minimally adequate. It states what the tool does but lacks behavioral context (e.g., return format, performance). For a read operation with no parameters, it's complete enough to understand the purpose but not rich in operational details.

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 tool has 0 parameters with 100% schema description coverage (empty schema). The description adds no parameter information, which is appropriate since there are no parameters. Baseline 4 applies as the description doesn't need to compensate for any parameter gaps.

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 verb 'Get' and resource 'devices on guest network', specifying the scope with 'VLAN 4'. It distinguishes from siblings like 'find_devices_on_vlan' by focusing on a specific VLAN, but doesn't explicitly differentiate from 'get_devices_by_interface' or 'find_device_by_mac' in terms of methodology.

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 implies usage when needing all devices on the guest network (VLAN 4), but provides no explicit guidance on when to use this versus alternatives like 'find_devices_on_vlan' (which might allow VLAN parameterization) or other device lookup tools. No exclusions or prerequisites are mentioned.

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