Where to watch

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

Annotations already declare readOnlyHint=true and openWorldHint=true, which inform the agent that the operation is safe and may return variable results. The description adds value by disclosing the data source (JustWatch via TMDB), the return format (provider names per access type plus regions), and that results are region-specific. This provides context beyond annotations.

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 description is highly concise (two sentences) with no unnecessary words. It front-loads the core purpose in the first sentence and provides supplementary details (data source, return content, prerequisite) in the second. 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?

Given the tool's moderate complexity (3 parameters, no output schema, read-only, open-world), the description is complete. It explains what the tool does, what it returns, and how to obtain the required id. The region parameter's format is documented in the schema, so the description does not need to repeat it.

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 the schema already documents all parameters. The description adds meaningful context by clarifying that the id parameter should come from search_movies/search_tv, which is not in the schema. This helps the agent understand the parameter's source.

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 clearly states the verb 'Find', the resource 'where a movie or TV show can be streamed, rented or bought', and the scope 'in a given country'. It distinguishes from sibling tools like get_movie by focusing specifically on streaming providers. It also mentions the data source (JustWatch via TMDB).

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?

The description gives explicit guidance: 'Get the id from search_movies/search_tv', telling the agent how to obtain the required id parameter. It implicitly indicates when to use this tool (when you need streaming provider info) and does not provide explicit exclusion criteria, but the purpose is narrow enough to avoid confusion.

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