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

Annotations already declare idempotentHint=true and destructiveHint=false/readOnlyHint=false; the description corroborates and enriches this by explaining the blocking wait, the two terminal outcomes (ready vs. ended with an error reason), and that a repeat call merely waits rather than re-uploading. That retry/polling behavior is genuine value beyond the structured fields, though auth or timeout details are not addressed.

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?

Three sentences, front-loaded with the action, then the possible outcomes, then the retry rule — no wasted preamble. The middle sentence ('It answers with the upload: ready to install with install_app, or ended with an error saying why') is slightly stilted in construction but still earns its place by covering the return states.

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 usefully covers the return states and the polling contract, and annotations carry the safety profile. For a two-parameter mutation tool this is nearly complete; only timeout/retry-limit expectations are absent.

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%, with both upload_id and storage_id documented including their formats and provenance, so the schema carries the parameter burden. The description adds only the implicit point that retries must reuse the same arguments; it offers no additional syntax or format guidance, making the baseline 3 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 ('Finish an upload'), names the precondition (file has arrived), and the side effect (Phonebox reads and stores the APK). It routes the agent to the correct sibling at each stage — create_app_upload before, install_app after — so it is clearly distinguishable from the other upload/install tools.

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: call after the file has arrived, and call again with the same arguments if processing is still in progress. It names install_app as the follow-on step. It stops short of stating any when-not-to-use case or a maximum retry/backoff policy, so it is clear but not exhaustive.

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