Watch Creator

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

The description goes beyond the annotations by disclosing that nothing is fetched and there is no cost, and that only the handle is stored. This is useful behavioral context beyond idempotentHint and destructiveHint. It does not contradict any annotations.

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 short, front-loaded, and easy to parse. There is minor redundancy with 'no cost' appearing twice, but it does not harm clarity.

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?

For a simple add-to-watchlist tool, the description covers the core behavior, the no-cost aspect, and the appropriate next step. The output schema exists, so return details are not needed. The only slight gap is the ambiguity of 'Stores the handle only' given that note and platform are also accepted parameters.

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 100%, and the schema already documents all three parameters, so the baseline is 3. The description's 'Stores the handle only' adds some context around the username parameter, but it does not meaningfully clarify note or platform beyond the schema.

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: 'Add a creator to your watchlist,' and clarifies that it stores the handle for later review. This clearly distinguishes it from siblings like catch_up_watchlist and unwatch_creator.

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 states the context ('so you can ask later what they have posted since') and explicitly points to catch_up_watchlist as the follow-up tool. It does not enumerate exclusions, but the primary usage context is clear.

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