serial_pair_record

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

With no annotations, the description carries the full burden, and it does disclose meaningful traits: interleaved output with [A]/[B] source prefixes, a HEX view fallback for wrong baud rates, and a hard 120s cap. However it omits operationally important behavior — whether it opens/exclusively holds the ports (relevant given serial_open exists), whether it blocks, and error behavior on a busy port. Useful but incomplete for a capture tool with zero annotation coverage.

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?

Three compact sentences with the core action front-loaded, followed by output-format details and the time cap. No filler. Slightly compressed for a 5 — the HEX-view clause is a justification rather than an instruction, but it earns its place by explaining the output.

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 exists, so return values need not be explained, and the description covers purpose, output shape, and the duration cap. Still, for a 5-parameter capture tool it leaves the required port arguments and the port-occupancy/interaction behavior undefined, which an agent would need for correct invocation.

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?

Schema coverage is 0%, so the description must compensate. It implicitly references the per-port baud parameters (the HEX-view 'wrong baud rate' rationale) and pins the seconds parameter to a 120s ceiling, which adds real meaning. But it says nothing about port_a/port_b naming or expected port identifiers, leaving half the parameters unclarified in both schema and description.

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: simultaneously listening to two serial ports and emitting a merged timeline log. The '(RS485 master-slave / dual-device debugging)' parenthetical sharpens the intent and sets it apart from the single-port serial_read/stream_capture siblings. No sibling is named, but the dual-port scope is distinctive enough to disambiguate.

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?

Gives a concrete usage scenario (RS485 master-slave dialogue, two-device joint debugging) that tells the agent when this tool beats the single-port alternatives. It does not state exclusions or prerequisites (e.g., ports must be free/not already opened via serial_open), so it stops short of explicit when-not guidance.

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