serial_list_ports

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

Annotations already declare readOnlyHint, openWorldHint=false, and destructiveHint=false, which covers the safety profile. The description adds that by-id and USB VID/PID are provided when available, and explains that bridge chips name the adapter rather than the MCU. That is useful behavioral context beyond annotations, but it stops short of describing output shape or ordering. With annotations carrying the safety burden, a 3 is appropriate.

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?

Two short sentences, front-loaded with the action. The second sentence is a useful caveat rather than filler, though it could be tightened. No waste.

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-param read-only list tool with annotations covering safety, the description is adequate. It explains what the listing contains and a gotcha about bridge chips, but does not describe return format or ordering, which would help an agent consume the result. Without an output schema, some of that burden remains on the description.

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?

Zero parameters, so baseline is 4. The description cannot add parameter meaning because there are none, and nothing about parameter semantics is missing or misleading.

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?

Clear verb+resource: 'List serial ports'. The second sentence adds content about what data is included (by-id, USB VID/PID) and a caveat about bridge chips. It does not differentiate from siblings like serial_port_status, which could also enumerate ports — no explicit distinction is drawn.

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 on when to use this versus alternatives such as serial_port_status or serial_read. The agent has to infer that this is for discovery. There is no exclusion or selection criteria stated.

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