list_devices

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

With no annotations, the description carries the full burden. It discloses that the tool is a read-only listing operation and details the output fields, which is useful. However, it does not explicitly state safety (e.g., no side effects) or any limitations, such as whether it reflects real-time connection status.

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 concise and front-loaded: it opens with the primary action, then lists the output details, and ends with a practical usage note. Every sentence earns its place with no 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?

For a simple tool with no parameters and no output schema, the description is complete enough: it covers what it does, what information is returned, and when to use it. It could explicitly mention that it is a safe read-only operation, but given the low complexity, the current description is adequate.

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 the schema fully covers this (empty schema, 100% coverage). The baseline for 0 params is 4, and the description adds nothing needed beyond that.

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 lists all registered devices and specifies the exact information it returns (address, IO channel counts, function modules, connection type). This distinguishes it from siblings like list_connections (connections vs devices) and scan_devices (discovery vs registered).

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?

It explicitly states when to use the tool: before controlling devices to confirm device address and available loop count. However, it does not explicitly mention when not to use it or compare against discovery tools like auto_discover/scan_devices.

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