Validate a render and estimate credits

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

Discloses that no credits are consumed, no render started, and that errors are returned for invalid movies or webhooks. Mentions authentication and environment variable dependencies. Lacks detail on the exact response structure (e.g., if only estimatedCredits is returned), but overall well-covered for a validation tool with no 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 a single paragraph of four sentences, front-loaded with the core purpose. Includes necessary details on authentication and error handling without excessive verbosity. Could be slightly more structured, but efficient.

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 role as a pre-render validation, the description covers when to use, what it does, authentication, and error handling. No output schema exists, so lack of response detail is acceptable. Sufficient for an agent to use correctly.

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%, and the description adds valuable context: asset references must be URLs and the agent must compose assets. The webhook parameter's purpose as a completion notification is clarified, adding beyond the schema's basic property descriptions.

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 tool validates a Movie definition, estimates credits without consuming them, and distinguishes from 'render' (which starts a render) and 'get_status' (status retrieval). The verb 'validate' and resource 'Movie definition' are specific.

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?

Explicitly advises to 'use this to preview cost and catch errors before calling render.' Also explains that authentication is via environment variables, guiding correct usage. Clear when-to-use and what not to expect (no render start).

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