is_installed

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

No annotations are provided, so the description must carry the full burden of disclosing behavior. It states the action but does not explicitly confirm that the operation is read-only and non-destructive, nor does it mention any side effects or prerequisites (e.g., whether the package must be a valid app identifier). For a check operation, the lack of an explicit 'does not modify the device' statement leaves uncertainty, especially since the tool could be expected to perform queries.

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?

The description is concise, consisting of two clauses in a single sentence. It front-loads the primary purpose and then clarifies the parameter. However, it redundantly mentions that the parameter is required ('Requires the `package_name` parameter') when the schema already marks it as required, adding slight bloat. Overall, it is efficient and well-ordered.

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?

Given the tool's simplicity (one parameter, no output schema), the description covers the core purpose and parameter meaning. However, it does not mention the return value or result format (e.g., whether it returns a boolean), which is essential for an agent to interpret the outcome. It also lacks guidance on edge cases like system vs user packages, which could be inferred from siblings but would strengthen completeness. For a low-complexity tool, this is a moderate gap.

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 description coverage is 0% – the schema only labels the parameter as 'Package Name'. The description adds semantic meaning by explaining that package_name is 'the name of the package to check', which clarifies what the string represents. While it does not elaborate on formatting or validation, it goes beyond the bare schema for a single required parameter, so it earns a 4.

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 clearly states a specific verb ('Checks') and resource ('if the specified package is installed on the connected Android device'), and it distinguishes from sibling tools like install_apk or all_packages by focusing on a single package existence check. The sentence is unambiguous and immediately tells an agent what this tool does.

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?

The description implies when to use the tool (when you need to verify a single package's presence), but it does not explicitly contrast with alternatives such as all_packages, user_packages, or get_all_packages, nor does it state when not to use it. Given the many package-related siblings, more explicit routing would improve clarity, but the core intent is understandable.

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