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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely useful billing behavior (credits charged on completed lookups, repeated requests may re-purchase the same data), which annotations cannot express. However the cost statements conflict internally — "at least 10 Nexscope credits" versus "1 credit per request" — leaving the agent unsure what a call actually costs.

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 core sentence is fine and front-loaded, but the tail is unedited pasted pricing boilerplate: "Rumble Video API View Pricing Gets Rumble video details by URL. 1 credit per request Actual supplier units are reported per request. Examples are not guaranteed prices." It repeats the opening sentence verbatim and has no punctuation or structure, wasting space and muddying the cost claim.

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, listing the returned fields is a valuable addition and the tool is simple (one required string param, read-only). What's missing is behavior on failure cases — invalid or non-Rumble URLs, private/removed videos — and a coherent single statement of cost, which matters since calls are billed.

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?

There is only one parameter and schema description coverage is 100% ("Rumble video URL."), so the schema already carries the full meaning. The description's "by URL" adds nothing beyond it. Baseline 3 applies when the schema does all the work.

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 ("Gets Rumble video details by URL") and enumerates what comes back (title, description, thumbnail, channel, publish date, view count, likes, dislikes, captions, media metadata). The URL-based lookup distinguishes it from siblings like social_rumble_search and social_rumble_channel_videos, though those siblings are never named explicitly.

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 "by URL" phrasing implies you need a known video URL rather than a query, which implicitly routes agents to social_rumble_search for discovery. But there is no explicit when-to-use/when-not-to-use statement and no mention of when to prefer social_rumble_video_transcript or social_rumble_video_comments instead.

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