serial_download

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

With no annotations, the description carries the full burden. It describes blocking behavior, two timeout semantics (idle_timeout for real failure, timeout as a safety cap), and progress logging to stderr. It doesn't mention return values or error details, but core behavior is well covered.

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 sentences, each substantive and front-loaded with the main purpose. No filler or redundant 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?

Covers prerequisites, blocking behavior, and timeout semantics thoroughly for a file download tool. The absence of an output schema means return values aren't described, but for a download operation the local_path and timeout behavior are the most critical aspects, and these are well covered.

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 covers all 6 parameters with descriptions (100% coverage), so baseline is 3. The description adds key nuance about timeout behavior beyond the schema, particularly the distinction between idle_timeout and total timeout, which elevates the score to 4.

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 downloads a binary file from a device over ZMODEM via an existing serial session, which is a specific verb+resource+protocol. This distinguishes it from siblings like serial_upload and serial_read.

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?

It provides clear context for use: requires an existing serial session and the lrzsz package (sz command). It doesn't explicitly name alternatives but the serial/ZMODEM framing implies when it should be used over raw read/write tools.

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