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

Annotations already declare idempotentHint=true, destructiveHint=false and readOnlyHint=false, so the safety profile is covered. The description adds two useful facts beyond that: this call kicks off the downstream pipeline (a real side effect) and it returns a job id for polling. It does not say whether the completion is final/irreversible or what happens on a stale parts list, so it is a modest addition rather than rich behavioral context.

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?

Two sentences, no filler, and the action-plus-consequence comes before the return/polling instruction. Every clause earns its place and nothing is redundant with the annotations.

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 five required parameters, no output schema and no nested objects, the description covers the essentials: what triggers the call, that it starts processing, and that the return is a job id to poll. It leaves minor gaps around the multipart-completion semantics (e.g. whether parts must be listed in order), but those are largely implied by the schema.

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 description coverage is 100% and every one of the five required parameters carries its own description, including the {PartNumber, ETag} part structure and the cross-reference to lunara_upload_video for videoId. The description adds no parameter-level detail beyond the schema, so the baseline 3 applies.

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 concrete action (notify Lunara that the bytes are uploaded) plus the consequence (pipeline starts), which is specific enough to separate it from lunara_upload_video and lunara_start_subtitle_job. It also names the return value, so an agent knows this is a terminal step of a multipart upload rather than a generic job starter.

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?

"Tell Lunara the bytes are uploaded so the pipeline can start" gives the triggering condition, and "poll with lunara_get_job" explicitly routes the agent to the correct follow-up sibling. It stops short of stating prerequisites (e.g. all parts uploaded via lunara_upload_video) or exclusions, so it falls just short of a 5.

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