Check a price now

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

Annotations already mark it read-only and idempotent; the description adds useful behavior: it performs a fresh page fetch, returns a change since last check, and deliberately creates no watch. This goes beyond the annotations without contradicting them.

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, each earning its place: when to use, what is returned, and the no-watch side effect. It is front-loaded and contains no filler.

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 one-parameter read-only tool, the description covers the call condition, the output fields, and the key side-effect distinction. No output schema exists, but the description supplies enough return information for an agent to know what to expect.

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 single url parameter is documented with a clear description including the https:// requirement. The description repeats 'any product URL' but does not add new parameter details; baseline 3 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 verb and resource: 'Call this tool for any product URL' to check a price, and it explicitly lists the returned data (price, currency, title, confidence, change since last check). It distinguishes itself from a generic web fetch and from watch tools by saying 'It creates no watch.'

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 gives clear when-to-use context: use it for a product URL because a generic web tool returns raw HTML without the price. It does not name sibling watch/history tools or give explicit when-not-to-use conditions, but the 'creates no watch' statement implies the boundary.

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