device_facts

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

readOnlyHint already declares this as a safe read, and the redundant "[READ]" tag adds nothing beyond it. The description does add real value by disclosing the returned content and the interface-name-list side output, which matters since there is no output schema. It stops short of any deeper behavioral context (auth/permission needs, error conditions).

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?

Front-loaded purpose statement followed by the sibling boundary and a labeled Args section - a clean, scannable structure. The "[READ]" prefix and minor line-wrapping are the only mild noise; nothing else is wasted.

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?

With no output schema, the description correctly carries the return-value burden and lists the salient fields plus the interface-name side output. For a single optional-parameter read tool this is nearly sufficient; slightly more detail on return shape or target-resolution failure would make it 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?

Schema description coverage is 0% and the sole parameter carries no documentation in the schema, so the description does the work. "Device name from config; omit to use the default device" defines both the value source and the omitted-value behavior, compensating well for the coverage gap.

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?

States a specific resource (device facts) and enumerates exactly what comes back: hostname, vendor, model, OS version, serial, uptime. It also carves out the boundary with the closest sibling by naming get_interfaces for per-interface state/speed, so an agent can tell the two apart without opening either schema.

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?

Explicitly routes one case to an alternative ("Use get_interfaces for per-interface state/speed") and explains the target argument's default behavior ("omit to use the default device"). It doesn't broadly position device_facts against the other device-level siblings (get_environment, device_health, get_optics), but the key ambiguity is resolved.

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