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

Adds genuinely useful behavior beyond the readOnlyHint/openWorldHint annotations: on login-gated videos it returns an unbilled empty result rather than failing or authenticating, and the call costs 1 credit. It stops short of describing pagination, ordering, or volume limits.

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?

Short and front-loaded, with the surprising failure mode and credit cost placed before invocation. The opening fragment 'Video comments.' merely restates the title and is the only wasted prose.

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 should sketch what comes back (comment fields, reply nesting, approximate counts); it only says 'including replies'. Also silent on the undocumented cache_max_age, leaving an agent without enough to call it optimally.

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 only 50%: `url` is documented but `cache_max_age` has no schema description, and the tool description says nothing about either parameter. It misses the chance to reinforce accepted URL forms or explain cache_max_age semantics, so the gap is uncompensated.

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+resource: retrieves public comments (including replies) on a Rumble video. Clear against most siblings, though it never explicitly contrasts with rumble_video, which an agent might also consider when it wants per-video data.

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?

Usage is implied by naming the resource ('comments on a Rumble video'), but there is no explicit when-to-use/when-not or routing to alternatives like rumble_video or rumble_transcript. The login-hiding note is behavioral context, not a selection guideline.

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