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

Goes well beyond the annotations by disclosing the return payload (one-off upload_url plus an exact curl command), the handoff contract (call complete_app_upload with the storageId), and hard limits (one file, up to 500 MiB, URL valid for one hour). These are exactly the operational constraints an agent must know for a non-idempotent, open-world upload tool.

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 compact sentences, front-loaded with the action and rationale, then the mechanics, then the limits. Every clause carries information an agent needs; nothing is filler.

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, and the description compensates by describing the return value and the follow-up call. For a zero-parameter tool whose real payload moves through a shell command, the description covers purpose, limits, and completion path completely.

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?

The schema has zero parameters, so there is nothing for the description to disambiguate; baseline is 4. The description correctly implies no arguments are needed and instead explains the out-of-band data flow.

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+resource ('Start an upload of your own APK') with immediate scope ('to install it on a phone'). It distinguishes itself from the sibling complete_app_upload by naming it as the required follow-up step, so an agent can place both tools in the workflow without opening a 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 ('your own APK, such as the debug build you just made') and explicitly routes to complete_app_upload with the returned storageId. There is no explicit when-not condition or mention of the alternative install path (install_app), but the trigger and the sequencing are unambiguous.

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