device_nac

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 behavioral context beyond the annotations by specifying the output contents (authenticated endpoints per port, auth method, VLAN) and the caveat 'where the device reports it,' which informs the user about potential data availability. This is meaningful supplemental information.

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 two concise sentences, front-loaded with the primary action and resource, followed by a brief elaboration on output details. Every word adds value, with no redundancy or unnecessary fluff. Excellent structure.

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 simple read-only listing nature, complete input schema with descriptions, and presence of an output schema, the description is sufficiently complete. It explains what the tool returns (NAC sessions with auth method and VLAN) without needing to restate the output schema. Safety annotations cover the operational side, and the description provides enough context for an agent to select and invoke the tool correctly.

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% coverage with descriptions for all three parameters (hostname, limit, offset). The description adds no parameter-specific semantics beyond implying that the device context is tied to 'hostname', which is already clear from the schema. The baseline of 3 applies because 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 tool's function: 'List network access control (802.1X / MAB) sessions on a device.' This uses a specific verb and resource, and adds detail about showing authenticated endpoints per port, authentication method, and assigned VLAN. It distinguishes itself from siblings like nac_list (global vs per-device) and port_security_list by specifying device scope and content.

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 the tool is used when you need to list NAC sessions on a specific device, providing clear context. It does not explicitly mention alternatives or exclusions, but the per-device scoping and focus on authentication details make the intended usage clear. No misleading guidance.

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