Serial Write

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

Annotations already mark this as destructive and non-idempotent. The description adds useful behavioral context beyond those hints: safety preflight is enforced unless explicitly skipped. This helps an agent understand the default safety behavior and the existence of an escape hatch.

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 sentences with no wasted words. The core action is front-loaded, and the important safety qualifier is stated immediately after.

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?

Given the output schema and annotations, the description supplies the essential prerequisite (open serial session) and the safety behavior. It could go deeper on preflight details or post-write response handling, but those are partially covered by schema and sibling context.

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 schema describes 4 of 6 parameters, so baseline credit applies. The description does not add meaning for sessionId or the nested safetyContext object, and it does not explain data encoding or line endings beyond the schema. It is adequate but does not compensate for the remaining gaps.

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 uses a specific verb and resource: 'Write bytes to an open serial session.' This clearly distinguishes serial_write from sibling tools like serial_open_session, serial_read, and serial_close_session.

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 establishes the key usage context: a serial session must already be open. It also indicates that safety preflight is enforced by default unless explicitly skipped. It does not explicitly name alternative tools, but the intended use case is clear.

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