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

With no annotations provided, the description carries the full disclosure burden and meets it thoroughly: it reveals cost (~12 credits, 0.6/result), that empty results and failures are never charged, and the caching behavior (free 24h hit, default always fresh). This is precisely the behavioral context beyond the schema that an agent needs for billing-aware invocation and retry decisions.

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 sentences, each earning its place: purpose plus alternative routing, cost model, and cache/failure policy. The 'lean streams[{url,type}]' shorthand is efficient but mildly cryptic for an agent, which keeps this from a 5.

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 3-parameter tool with no output schema and no annotations, the description compensates strongly by stating the return shape (url, type), cost, failure billing policy, and cache behavior — everything needed to call it correctly. Minor unspecified details such as pagination, sort order, and the explicit response array wrapper prevent a higher score.

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%, so the baseline is 3, and the description adds value on top: it ties the limit parameter to per-result billing (0.6/result) and the cache parameter to a free hit, which directly informs how an agent selects values. It correctly leaves URL-format and default semantics to the schema rather than repeating them.

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 identifies the resource ('Rumble channel uploads') and the lean output shape ('streams[{url,type}]'), which conveys that this tool lists a channel's uploads in minimal form. It distinguishes itself from the sibling rumble_video_details by explicitly directing rendition-metadata needs elsewhere. It stops short of a 5 because the verb is only implicit and the 'lean streams[{url,type}]' notation is terse.

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 explicitly names the alternative ('call video-details') and the condition for choosing it ('for rendition meta'), establishing a clear lean-vs-detailed split. It doesn't state comprehensive when-to-use/when-not-to-use criteria, but the context and cost contrast give an agent enough to route correctly.

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