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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false), so the bar is lower, yet the description still adds real context: the result is stable across chats/assistants and the call requires PN_ASSISTANT_TOKEN. It does not say what happens if the token is absent or how large the list may be, but the auth precondition is the important disclosure for a zero-parameter read.

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 short sentences with no filler: the scope constraint comes first and the auth requirement second. Every clause carries information an agent needs before calling.

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 zero-parameter, non-destructive list with no output schema, the description supplies the two things that matter: which device's app list this returns and the token requirement. Only the shape of the returned entries is unaddressed, which is a minor gap for such a simple read.

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 tool takes no parameters, so there is nothing for the description to disambiguate beyond the implicit scope of 'the person's persistent phone'. Baseline 4 applies for a zero-parameter tool, and the description does not confuse matters with phantom options.

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 ('List the apps installed') and scopes it to the 'persistent phone, the same in every chat and assistant', which is the key distinction from the sibling list_apps and list_store_apps. It never names those siblings explicitly, so the differentiation must be inferred from the qualifier rather than stated outright.

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 phrase 'persistent phone, the same in every chat and assistant' implies when this tool applies (stable device inventory rather than the current session's device), but there is no explicit when-to-use/when-not framing and no alternative tool is named. An agent can reason its way to the right choice, but only indirectly.

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