router_capabilities

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the context that these are the methods 'allowed by this MCP server', implying a restricted set. It does not contradict annotations, but it adds little beyond what annotations provide. There is no description of output format or side effects, though side effects are covered by annotations.

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, well-structured sentence with no wasted words. The key information (listing method signatures, read-only scope, server allowance) is front-loaded, making it easy for an agent to parse quickly.

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?

For a zero-parameter tool with annotations covering safety, the description is largely sufficient. However, since there is no output schema, the agent is left to infer what 'list method signatures' returns exactly—whether it's a flat list of signatures, a mapping of object names to signatures, or something else. This ambiguity could affect how the agent interprets the response. Additional clarification on the response format would make it completely complete.

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 zero parameters, and schema coverage is 100% (empty properties object). There is nothing for the description to explain about parameters. The baseline of 4 for 0-parameter tools is appropriate; the description does not need to compensate for any undocumented parameters.

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 states a specific verb ('List') and a precise resource ('method signatures for the read-only ubus objects allowed by this MCP server'). It clearly distinguishes itself from sibling tools that query actual router data (stats, routes, neighbors, etc.) by focusing on available method signatures rather than data itself.

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 for discovering what read-only ubus methods are available on this server, which contrasts with the data-returning sibling tools. However, it does not explicitly state when to use this tool versus alternatives, nor does it provide exclusions (e.g., 'use this before calling other tools to see allowed methods'). The context is clear but not fully explicit.

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