serial_list_ports

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 enumeration covers 'this machine' and that ST-Link VCP ports get a marker, which is genuine behavioral detail. It does not state that the call is non-invasive (does not open or lock ports), nor whether enumeration can be slow or miss virtual/hot-plugged ports.

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 with the core action, and the field list (path, description, VID:PID, serial number) is useful pre-call context. The trailing 'Returns: List of serial ports with details' sentence is largely redundant given an output schema exists, so it is not perfectly lean.

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?

An output schema already documents the return shape, so the description need not have restated it; what it does provide — the machine-local scope and the [ST-Link VCP] marker convention — is exactly the kind of thing the schema cannot express. Nothing essential for a zero-arg enumeration tool is missing.

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 takes zero parameters, so there is no parameter semantics to explain — the baseline of 4 applies. The description correctly adds no parameter chatter that would be irrelevant here.

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 verb and resource (list / serial ports) plus the scope: ports on this machine, not remote ones. It also differentiates from the nearby stm32_list_probes by clarifying that ST-Link VCP ports are annotated in the output rather than being a separate probe enumeration.

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?

Usage is only implied: the natural inference is 'call this before serial_connect to learn the device path', but the description never says that or names serial_connect as the follow-up. No prerequisites, exclusions, or note about when port enumeration would be empty or unhelpful.

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