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

Annotations declare readOnlyHint=true and openWorldHint=true, so the agent knows it's a safe read operation. The description adds the crucial note that availability changes and should be treated as a snapshot, which is valuable external context. It does not disclose pagination or rate limits, but given the annotations, this is adequate.

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 sentences, efficient, and front-loads the core purpose and the critical dependency on a TMDB id. The snapshot warning is a concise addition that 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?

For a read-only, idempotent tool with 100% schema coverage, the description sufficiently covers what the tool does and the key caveat about data volatility. There is no output schema, so return format isn't expected, but the description doesn't mention whether results include price or link details, which could be helpful. Nevertheless, it is adequate for the 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?

The schema already fully describes all three parameters: id requires a numeric TMDB id from movies_search, media has enum with default, and region is a two-letter code with default. The description does not add any semantic detail beyond the schema, but since coverage is 100%, it meets the baseline.

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 that the tool finds streaming/rent/buy availability by country and provider, and it references the required input (TMDB id) and the data source (movies_search). This distinguishes it from sibling tools like movies_details or movies_search.

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 explicitly notes the need for a TMDB id from movies_search, which serves as a prerequisite. It also warns about availability changes, suggesting use as a snapshot. However, it does not explicitly contrast with alternatives like movies_compare_lists or person_watch_path, but the id requirement provides clear usage context.

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