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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds that the result contains season metadata and episode references, but with an output schema present even that return hint is largely redundant, leaving only modest added context.

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 tight sentences with zero filler, and the core action is front-loaded before the ID-provenance guidance. Every sentence earns 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 an output schema present the description needn't explain return values, and it correctly focuses on what an agent must know: the ID's origin and format. Country/language behavior is left to the schema, which is acceptable but leaves the description slightly thin for a 3-param tool.

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%, with the id format (tss[0-9]+) and country/language defaults fully documented in the schema, so the baseline is 3. The description's note that the id is a raw GraphQL season id adds marginal value over the schema's own regex example.

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 gives a specific verb and resource ('Fetch a JustWatch season') and qualifies the input as a 'raw public GraphQL ID', which distinguishes it from list-style siblings like justwatch_show_seasons. It does not explicitly name those siblings, but an agent can still tell what this retrieves.

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 states the prerequisite directly: 'use a season ID returned from a show's season list', telling the agent where the required id comes from. It stops short of naming an alternative tool or an explicit when-not-to-use, so it is clear context rather than full routing.

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