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

Annotations already declare readOnlyHint and openWorldHint, but the description adds genuinely non-obvious behavior: the billing model ('billed like an API request; listing plugins bill one unit per result page they fetch') and the pagination-driven cost of max_results. It stops short of noting rate limits, failure modes, or whether scraping can return partial pages.

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 purpose and return shape, then constraints, which is the right order. The trailing standalone 'Returns JSON.' repeats the earlier 'returns the properties as JSON' and is the one sentence that does not earn its place.

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?

With no output schema, the description compensates by listing the response fields, and it covers cost, pagination, and the date requirement for prices. Minor gaps remain around defaults for adults/rooms and how proxy_country affects results, but nothing that would cause a mis-call.

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%, so the baseline is 3; the description earns above that by explaining the cross-parameter dependency that the schema only hints at (prices require checkin/checkout) and by framing max_results as a cross-page collection budget rather than a page size.

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 opens with a specific verb and resource ('Searches Booking.com for `location`') and enumerates the returned fields (name, price, reviewScore, address, coordinates, image, url), which makes it unmistakable against generic siblings like browse_page or google_search.

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 one useful conditional ('Prices only appear when check-in/check-out dates are given') and a cost-avoidance nudge ('keep max_results modest'), but it never says when to prefer this over zillow_search, google_shopping, or maps_place_details, so tool routing is left to inference.

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