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

With only a title annotation, the description carries the full burden and delivers: it probes the object, deletes rejected bytes on signature/size mismatch, records the asset, and returns a real placeholder_id. The destructive deletion behavior is disclosed up front — a trait no annotation covers.

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 and dense with zero filler; the arrow notation compresses the register→placeholder_id→join_videos flow efficiently. Telegraphic style is slightly terse but every clause earns its place.

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?

No output schema exists, yet the description explains the return (real placeholder_id) and the alternative output (public_url). For a 4-param validation tool with chaining implications, an agent has everything needed to call it correctly.

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, but the description adds pipeline meaning: it ties `path`/`type` to the request_upload response and explains that the confirmed id feeds var2_join_videos, going beyond the field-level docs.

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 compound verb+resource (validate + register an uploaded file) and immediately scopes it against the sibling that created it (var2_request_upload). The mention of the resulting placeholder_id for var2_join_videos chaining lets an agent place it in the pipeline without opening any 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?

Explicit when-to-call (with `path` + `type` from the request_upload response AFTER the PUT succeeds) and explicit when-to-skip (optional; skip if you only need `public_url`). Both the trigger and the exclusion are named, leaving nothing to inference.

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