apps_launch

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

Annotations already declare the mutation and open-world profile (readOnlyHint=false, openWorldHint=true, idempotentHint=false). The description adds genuinely useful context beyond them: the operation is bounded by an 'enabled Launch/Exit scope', new I/O permissions require human consent, and no draft is saved. It omits return/async behavior, but adds real value over the annotations.

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 action, then prerequisites, then param guidance, then exclusions, in a compact set of sentences with little waste. The 'new real I/O permissions still require the person' clause is slightly opaque but earns its place as a consent caveat.

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?

For a non-read-only, open-world mutation tool with no output schema and 0% schema coverage, the description covers scope, prerequisite, one param, and one exclusion. It leaves gaps around async behavior (operationId, apps_operation_status sibling), the required expectedPackageDigest, and idempotency, so it is adequate but not complete.

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 0% across four parameters, so the description carries the full documentation burden. It clarifies only replaceInstanceId; appId, operationId, and expectedPackageDigest (a required param, notably) receive no explanation, leaving most parameters undocumented in both schema and description.

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 description gives a specific verb+resource: 'Launch or focus a saved App on the device.' The phrase 'saved App' and the focus behavior distinguish it from siblings like apps_create and apps_save, though it never explicitly contrasts with apps_open, which an agent might reasonably confuse it with.

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 states an explicit prerequisite ('Read apps_state first') and conditional guidance for replaceInstanceId ('only after deciding to replace that known target'), plus an exclusion ('Does not save a draft'). It stops short of naming an alternative tool to use when the conditions don't hold, so it is clear context without explicit alternatives.

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