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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds nothing further: no note about what an 'episode' payload contains, no localization behavior for country/language, no mention of error behavior for malformed ids.

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?

A single short sentence with the resource and the disambiguating qualifier front-loaded; nothing is padded. It is terse to the point of under-specification, but that is a completeness problem rather than verbosity.

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?

The tool is simple, the output schema covers the return value, and all three parameters are fully documented in the schema. What is missing is id provenance — nothing tells the agent to obtain a tse-id from justwatch_season_episodes or justwatch_search, which is the one piece of context a by-id lookup needs.

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 the id format (tse[0-9]+), country and language defaults are all documented in the schema itself. The description's only contribution is the phrase 'raw id', which is redundant with the schema's regex example. Baseline 3 applies.

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 and resource ('JustWatch episode lookup') and adds the qualifier 'by raw id', which hints at the difference from listing siblings like justwatch_season_episodes. However, it never names an alternative or explains how this differs from justwatch_title_by_id / justwatch_season_by_id beyond the noun 'episode'.

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?

No when-to-use guidance at all. The description does not say that this is for direct id-based fetches as opposed to justwatch_search, nor does it point to the tool that produces episode ids. The agent must infer the routing entirely from the name.

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