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

Goes well beyond the readOnly/idempotent annotations by stating nothing is created, reserved or charged, that the call is free, and what is returned: the balance, whether it covers the price, this key's remaining daily cap, and canStart/blockedBy. That is decision-grade behavioral context an agent cannot infer from annotations alone.

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?

Front-loaded with the core guarantee (price, read-only, free) and then mode-by-mode detail; no filler. The sentences are long and clause-heavy, which slightly slows scanning, but every clause carries information.

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?

With no output schema, the description carries the return-value burden and does so — balance, coverage sufficiency, canStart/blockedBy, daily cap — and closes the loop on the follow-up creation call. Nothing an agent needs to price and then act is missing.

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 already 80%, and the description still adds real meaning: the duration ranges are attributed per mode (4-12 for motion_clip, 8-90 for stills) and the tool parameter is scoped to stills-only with a documented default. The only gap is aspect_ratio, which is unexplained.

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?

States a specific verb and resource ('the exact credit price of a video BEFORE it is made') and enumerates both modes with the concrete creating tool each maps to (autoshort_generate_motion_clip, autoshort_generate_chat_video / autoshort_generate_video). An agent can distinguish this from autoshort_estimate_cost or autoshort_get_credit_balance without opening a schema.

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?

Explicit sequencing: 'Tell the user the price, then call the creating tool' — this is a pre-flight quote, not the creation itself. Each mode names the downstream tool, so the agent knows exactly which sibling to invoke after pricing.

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