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

With no annotations, the description carries the full burden and does so well: it discloses cost (2 credits per minute), async behavior and the polling pattern, that result links expire in 1 hour, and where segments are served from. It stops short of stating auth/permission requirements or rate 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?

Four short sentences, front-loaded with purpose and output, then operational facts (cost, async, expiry). Nothing is redundant or padded.

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 no-annotation, no-output-schema tool, the description covers the return value, async polling contract, cost, and link expiry, which is nearly everything an agent needs. Minor gaps remain: no guidance on choosing heights/segment_seconds values and no permission requirements.

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 67%: url and heights are documented in the schema, but segment_seconds has no description anywhere. The description only loosely gestures at parameters ('several quality levels') without adding format, range, or default meaning beyond the schema, so baseline 3 is appropriate.

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 ('package a video ... as HLS') plus the defining characteristic of the output (several quality levels, master playlist) which separates it from generic converters like convert_media or compress_media in the sibling list. An agent can tell what it produces without opening the 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?

Gives clear context for use (adapting to slow connections for web playback) and routes follow-up work explicitly: 'Long jobs return a job_id; poll it with get_job.' It does not, however, state when not to use it or contrast it with nearby siblings such as extract_audio, trim_media, or compress_media.

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