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

The description goes well beyond the annotations by disclosing that free renders contain a watermark, take ~1–3 minutes on the CPU render lane, and return a renderId plus interactive page URL. These behavioral details help the agent set expectations, even though annotations already indicate non-readonly and idempotent behavior.

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?

Three dense sentences front-load the purpose, then explain required and optional inputs, and finally disclose output and timing. Every sentence earns its place with no filler, making it easy to scan.

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 tool with no output schema, the description adequately explains what is returned, how to poll for the result, and the expected runtime. It also ties into sibling tools (get_motion_tool and get_motion_render) to form a complete workflow.

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 covers 75% of parameters, and the description adds useful semantics by explaining that variantId comes from get_motion_tool and defaults to the tool's default variant, and that fields hold text values keyed by field key. This adds meaning beyond the raw schema, though some details are redundant.

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 opens with 'Render a customized MP4 with a Mographr free tool', a specific verb+resource pair that clearly states the action and object. It distinguishes itself from sibling tools (get_motion_tool, get_motion_render, list_motion_tools) by focusing on the rendering action rather than listing or retrieving.

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 clearly implies when to use this tool: when you need to render a customized MP4 after obtaining a slug and optional ids from get_motion_tool, and it directs polling to get_motion_render. It provides solid contextual guidance, though it does not explicitly enumerate exclusions or contrast with all sibling tools.

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