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

Annotations already indicate a non-read-only operation. The description adds the useful constraint that names are unique per user, which implies a potential conflict on duplicate names. However, it does not disclose response behavior, error handling, or side effects beyond that constraint, so transparency is adequate but not rich.

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 concise and front-loaded, with two short sentences that convey the essential purpose and a key constraint. There is no redundancy or filler; every word contributes to understanding.

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 tool's moderate complexity (4 parameters, no output schema), the description combined with the rich schema and annotations is fairly complete. It explains the tool's purpose and the uniqueness constraint, but could optionally clarify what the response contains or how errors are surfaced. However, the schema covers parameter semantics, making the overall information sufficient for typical use.

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 input schema provides 100% coverage of all four parameters with detailed descriptions, so the baseline is 3. The description adds value only by reinforcing the uniqueness of the name parameter but does not add further meaning to the other parameters beyond what the schema already provides.

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 action ('Create a new Stock Tracker') and the resource, with a helpful definition of what a Stock Tracker is ('a place for instruments you want to keep an eye on'). This effectively distinguishes the tool from siblings such as add_to_watchlist or update_watchlist, which operate on existing trackers.

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 usage by the verb 'create' and the resource context, but it does not explicitly state when to use this tool versus alternatives (e.g., update_watchlist) or mention any prerequisites or exclusions. The uniqueness constraint ('Names are unique per user') hints at a requirement but offers no direct comparison to sibling tools.

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