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

Annotations already declare openWorldHint=true, idempotentHint=true and destructiveHint=false, so the safety and idempotency profile is covered structurally. The description adds genuinely useful billing context (1 credit per successful resolution) and a client-side fallback procedure, but does not discuss retry semantics, failure modes beyond download timeout, or what happens on a failed resolution re: credits.

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 action, then limitations, alternative routing, fallback, and cost. Four tight sentences, none redundant, no filler.

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 usefully states the return value (a resolved watermark-free URL) and covers cost, prerequisites, and failure handling. It is nearly complete, though it omits credit-refund behavior on failure and any timing or rate-limit expectations.

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 description coverage is 0%, so the description carries the load: it clarifies that videoUrl is a share URL from a supported app/site (not a direct media URL) and that operationId is required alongside a credit spend. However, operationId's purpose and lifecycle are never explained, leaving half the parameters semantically thin.

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 concrete verb and resource: resolve a share URL to a watermark-free data.video URL, naming supported sources (TikTok, X). It also distinguishes itself from submit_subtitle_task, so an agent can tell the two apart without opening either 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?

Explicitly scopes when it applies (remote share URLs from supported apps/sites), when it does not (hardcoded subtitles or burned-in overlays), and names the alternative path for that case (upload then submit_subtitle_task). It also prescribes fallback behavior for client download failure.

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