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

Beyond readOnlyHint=true, it discloses polling cadence (3s), the state machine (queued -> processing -> uploading -> completed), link lifetime (24h) and re-fetch semantics, file retention (30 days), cost placement, SSE streaming support, and the exact error codes it can refuse with. This is far more than the annotations carry.

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 behavior, then ordered into pricing, streaming, retention, and refusals. It is long and dense, and the error-code catalog could be tightened, but nearly every clause carries actionable information.

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?

There is no output schema, so the description has to explain return values, which it does (download_path, download_url, captions_url, download_url_unavailable, files_kept_until). Combined with polling behavior and failure modes, an agent has everything needed to call and interpret this tool.

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. The description restates the job_id-optional behavior already documented in the schema and adds little new per-parameter detail (no format hints for job_id or project_id beyond the vx_/vp_ prefixes already in the schema).

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 first sentence names a specific verb and resource with scope: 'Follow one video export to completion and return its download links.' It explicitly distinguishes itself from the sibling that starts exports (video.export_create), so an agent can pick between them without inspecting schemas.

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?

It names the prerequisite call (video.export_create), what to pass (job_id), and the fallback behavior when job_id is omitted. It adds negative guidance too: on a failed/cancelled/expired job the correct action is a new export, not a retry here.

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