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

The description claims 'Reads stored data only,' which indicates a read-only operation, but the annotations set readOnlyHint to false. This is a direct contradiction between the description and the structured annotation, so behavioral transparency fails.

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 two sentences with no wasted words. It front-loads the core question and thresholds, then adds the prerequisite and data-source clarification.

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 zero-parameter tool with no output schema, the description thoroughly covers purpose, thresholds, change percentage, and the watch_refresh prerequisite. An agent has enough information to invoke it correctly.

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?

This tool has zero parameters and 100% schema description coverage, so there are no parameter semantics for the description to add. The zero-parameter baseline applies.

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 states a specific action and resource: 'Answer whether anything you watch got cheaper' and defines the exact alert criteria (at/below target_price or down 5% since previous observation, with change %). This clearly distinguishes it from siblings like watch_list or watch_refresh.

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 explicitly provides the prerequisite 'run watch_refresh first' and clarifies that it reads stored data, giving clear when-to-call context. It does not explicitly name alternatives to avoid, but the usage context is sufficient.

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