Where to watch

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

Annotations already declare readOnlyHint and openWorldHint. The description adds valuable behavioral context: the return structure (provider names per access type, fallback with available_regions). It does not contradict 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 two substantive sentences plus a short instruction. It is front-loaded with the main purpose. Minor redundancy (e.g., 'JustWatch data via TMDB' could be tighter) but overall concise and well-structured.

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 output schema exists, the description need not detail return values, but it does describe the key return structure (provider names, fallback). It covers the essential edge case of no data and region handling, making it complete for this tool's complexity.

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 coverage is 100% for all three parameters. The description adds value by instructing the agent to 'Get the id from search_movies/search_tv', which clarifies the parameter source beyond the schema's description. This subtle guidance enhances semantics.

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' and the resource 'watch providers for a movie or TV show', distinguishes from siblings like search_movies and get_tv by specifying the exact functionality (streaming, renting, buying via JustWatch) and hints at the necessary ID source.

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 provides clear context on when to use this tool (to find streaming options) and gives a fallback behavior ('if it has no data, returns available:false plus available_regions to retry with'). It also specifies the prerequisite source for the 'id' parameter. However, it does not explicitly contrast with sibling tools like search_watch_providers.

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