OPNSense MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the search functionality but doesn't describe what the tool returns (e.g., a list of matching rules, their details, or error handling), whether it's read-only, or any performance considerations like rate limits. This leaves significant gaps for a tool that likely queries a security system.

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 functionality ('Find firewall rules by description') with zero wasted words. It's appropriately sized for a simple search 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 the lack of annotations and output schema, the description is incomplete. It doesn't explain what the tool returns (e.g., a list of rule objects, success status), behavioral traits like safety or side effects, or how it differs from sibling tools. For a firewall-related tool with potential security implications, this is inadequate.

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 single parameter 'description' documented as 'Description to search for'. The tool description adds no additional meaning beyond this, such as search semantics (e.g., partial matches, case sensitivity) or examples. Baseline 3 is appropriate since the schema does the heavy lifting.

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 ('find') and resource ('firewall rules') with a specific search criterion ('by description'), making the purpose unambiguous. However, it doesn't explicitly differentiate from sibling tools like 'list_firewall_rules' or 'get_firewall_rule', which would require a 5.

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 like 'list_firewall_rules' (which might list all rules) or 'get_firewall_rule' (which might retrieve a specific rule by ID). The description implies usage for searching by description but doesn't mention exclusions or prerequisites.

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