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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safe-read profile is covered. The description adds that it returns 'normalized metadata and offers' and that the id is 'raw JustWatch GraphQL', but says nothing about auth, rate limits, or how offers are scoped by country/language. Baseline credit is appropriate given annotation coverage.

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 purpose is well front-loaded, but the description then inlines per-parameter documentation that duplicates the schema field descriptions word-for-word. That redundancy wastes space against a 100%-covered schema, even though the overall length is modest.

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 tool is a simple 1-of-3-required-parameter lookup. Purpose, id format, defaults, and the search alternative are all present; only the sibling-id routing among justwatch_* tools is left implicit.

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%, so id, country, and language are already fully documented with defaults in the schema. The description restates the country/language defaults verbatim rather than adding syntax or edge-case meaning, so it earns the baseline of 3, not more.

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?

States a specific verb+resource ('Looks up an episode') and pins the identifier format with a concrete example ('tse5550494'). An agent can immediately tell this is a by-id lookup rather than a search, and the description explicitly routes text queries elsewhere.

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?

Names an alternative and its condition: 'Use justwatch_search to search JustWatch titles,' which implies this tool is for when you already hold a raw id. It does not address other id-based siblings (justwatch_season_by_id, justwatch_title_by_id) or downstream episode offers, so no explicit exclusions.

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