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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, so the safety profile needs no restating. The description earns credit for disclosing what comes back — lowest/median/highest price, current low/typical/high position, last price change with timing, and notification rules — which matters since there is no output schema. Return volume, pagination, or ordering of results is not addressed.

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?

Three short sentences, front-loaded with what the tool answers, then usage examples, then scope options. Little waste; the '(processor restock_diff)' aside is the only phrase that does not pay for itself.

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 four-parameter, zero-required read-only tool with full schema coverage and no output schema, this covers purpose, return contents, and all scope modes. An agent has everything needed to decide to call it and how.

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 100%, so the parameter definitions already do the work and the baseline of 3 applies. The phrase 'All of them, one tag, a name search, or one monitor' usefully establishes that no arguments means everything, a fact the schema does not state. The in_stock filter and the single-match caveat on 'watch' are left entirely to 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?

Opens with a specific query object: which product monitors are in stock, at what price, with price history and notification rules. That is clearly distinct from siblings like get_watch or list_watches in intent, though it never names a sibling to route against. The parenthetical '(processor restock_diff)' is internal jargon that adds little for an agent.

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 two concrete user-intent examples ('what on my wishlist is back in stock?' and 'is anything cheap now?') plus the four scope modes, which tells an agent when this tool fits. It stops short of stating when-not to use it or which sibling to prefer for a single monitor's raw details.

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