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

Annotations declare readOnlyHint=false, which is counterintuitive for a lookup, and the description explains why: 'Uses one read and saves the result in the user's Puley history.' That is exactly the kind of side-effect disclosure annotations cannot convey, and it is consistent with the annotations. It stops short of saying what happens on a no-match or which regions JustWatch covers poorly.

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 return-value enumeration is front-loaded, followed by parameter notes and then a freshness caveat, so the important content comes first. The middle sentence is an overlong run-on with mixed commas ('whether it's included with a subscription, free, free with ads, to rent or to buy...'), which slightly hurts scannability, though little of it is truly wasted.

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 properly compensates by describing the shape of the result, and it also covers side effects and data freshness for a 3-parameter tool. What is missing is edge-case behavior (title not found, ambiguous matches, unsupported country), which matters for a lookup against an external catalog.

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 0%, so the description must carry parameter meaning, and it largely does: country is explained as a two-letter code or name with concrete examples (US, GB, IN, DE, BR, JP), and year is given a real purpose ('to tell remakes apart') rather than being left as a bare integer. Only 'title' is left unelaborated, which is acceptable since it is the required, self-evident input.

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?

It states a specific verb-like outcome (find where a film/show can be watched, in a given country) and enumerates exactly what is returned: services, monetization type, price, quality, seasons, deep link, sourced from JustWatch. That is far more specific than the name alone. It loses a point because it never distinguishes itself from close siblings such as check_watch_now, get_watch, or watch, which an agent must guess between.

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?

There is no explicit when-to-use / when-not-to-use guidance and no named alternative among a large sibling set that includes check_watch_now, get_watch, list_watches, and watch. The phrase 'right now' and the note that 'services add and drop titles monthly' hint at a freshness use case, but the agent is left to infer routing entirely on its own.

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