watch_channels

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

With no annotations provided, the description carries the full burden. It discloses the stateful side effect ('mark them seen'), the 'since the last call' behavior, the first-run cap, and the channels.json fallback with an environment variable. It does not cover auth or rate limits, but the key behavioral traits are transparent.

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 three short sentences with the core behavior front-loaded. Every sentence adds operational value—core action, channel input syntax, and the first-run edge case—with no filler or repetition of schema defaults.

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 describing return values is unnecessary. The state directory, environment variable, default path, and first-run behavior are covered, but languages and with_transcript have no semantic explanation anywhere, and there is no guidance about prerequisites or error cases.

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 description coverage is 0%, so the description must compensate. It adds real meaning for 'channels' ('@handles / UC ids', empty means read channels.json) and mentions max_new_per_channel for first-run behavior, but leaves languages and with_transcript entirely unexplained beyond their parameter titles.

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 opens with a specific verb and resource: 'Return videos published since the last call and mark them seen.' This clearly distinguishes watch_channels from list_channel_videos by emphasizing stateful filtering and a side effect, so an agent can tell them apart without opening schemas.

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 implies a polling/check-for-new-videos use case and explains input behavior, but it never explicitly says when to prefer this tool over siblings like list_channel_videos. The 'since the last call' wording gives context, yet no exclusions or alternatives are named.

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