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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and external-access character are covered. The description adds value by disclosing that it fetches a live JustWatch page and summarizes its availability/offer content, but says nothing about latency, region dependence, or pagination/limits.

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?

Two sentences, front-loaded with the purpose and the summarized dimensions, followed by the constraint and the alternative tool. Efficient overall, though the 'Pass exactly one of path or url' line duplicates the schema text verbatim.

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?

An output schema exists, so return values need not be explained, and the description still previews the summary contents well. Combined with readOnly/openWorld annotations, an agent has enough to call it correctly; region-scoping of availability results is the only notable omission.

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% and both parameters already state 'Pass exactly one of path or url,' so the schema carries full semantics. The description only repeats that same constraint rather than adding format examples or error behavior beyond 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?

The description states a specific verb (fetches) and resource (JustWatch title page) and enumerates what it produces: provider availability, monetization buckets, formats, price ranges, and best rent/buy/free/subscription options. It distinguishes itself from the sibling justwatch_title by calling that tool out for 'title details.' Clear and concrete.

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 names one alternative (justwatch_title) for getting title details, implying this tool is for availability/summary analysis. However, the routing against closely related siblings like justwatch_title_offers and justwatch_title_media — which overlap heavily with the 'offers/price ranges' output described here — is left unaddressed.

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