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

Annotations already declare the write/idempotent/non-destructive profile, and the description adds real context beyond them: the alert fires on a hold-to-sell valuation signal change, the Pro gating, and that the response lists exactly what changed. It doesn't cover auth or delivery specifics, but it goes well past the annotation surface.

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?

Front-loaded with the action, then scope, mechanism, and usage in short declarative sentences. Slightly more detail than strictly needed (the hold-to-sell explanation), but every sentence contributes information an agent would otherwise lack.

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 single-parameter toggle with no output schema, the description covers action, scope, gating, trigger condition and response shape ('lists exactly what changed'), while annotations carry the safety profile. Nothing essential to a correct call is missing.

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?

With one parameter at 100% schema coverage, the schema already documents the boolean toggle. The description nonetheless adds semantic scope the schema lacks: that the toggle governs email alerts for the entire watchlist rather than individual stocks, which is meaningful for correct invocation.

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 (turn on/off), resource (watchlist email alerts) and scope (whole watchlist, not single stocks), which cleanly separates it from the per-stock siblings like add_to_watchlist and get_stock_verdict. An agent can identify the operation without opening the schema.

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 clear trigger ('Use it when the user asks for this change to their own account') and a scope exclusion ('covers the whole watchlist, not single stocks'; 'no price-target alerts'). It stops short of naming a sibling alternative for per-stock alert changes, so it is strong but not fully explicit about when-not.

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