write_and_read

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 line_ending is auto-appended, wait_for causes waiting for a prompt string, and all data is logged. These behavioral details go beyond the schema and are valuable for the agent.

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 well-structured: a clear main action, then prerequisites, behavioral notes, and an Args list. It is not overly verbose and every part adds necessary information.

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?

The description, combined with the presence of an output schema, provides sufficient context for effective use. It covers prerequisites, behavior, and side effects like logging, though it leaves return value format to the output schema.

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 0% description coverage, but the description's Args section fully explains each parameter: command, wait_for, and timeout, including optionality and meaning. This completely compensates for the schema 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?

The description clearly states the tool sends a command to a serial port, receives a response, and returns it. It also specifies the prerequisite of connecting, distinguishing it from sibling tools like list_ports and connect.

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 explicitly instructs to execute connect beforehand, providing clear sequential context. It does not explicitly name alternatives or exclusions, but the purpose and sibling names make the appropriate usage scenario evident.

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