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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds the genuinely useful behavioral fact that the output is a lookup table of app_id→name pairs intended as a scoping input for other tools. It says nothing about result size or pagination, which is the only meaningful gap.

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 sentences, both front-loaded: what it returns first, how to use it second. No restatement of the tool name or 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?

With no parameters and no output schema, the description carries return-value burden and does so by naming the two returned fields and the downstream role of app_id. Only pagination/result-size behavior is unaddressed, which is minor for a small registry listing.

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 zero parameters, so there is nothing for the description to disambiguate; baseline applies. The description instead clarifies the semantics of the returned app_id as the scoping key used by other tools, which is bonus value.

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 registered apps") and even declares the returned fields (app_id + name), so an agent knows exactly what comes back. It is trivially distinguishable from the sibling listing tools (list_coupons, list_plans, list_subscriptions) by resource.

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?

"Use this first to discover valid app_id values, then pass one to the other tools" gives an explicit workflow ordering and downstream purpose, which is exactly what an agent needs for a discovery tool. It stops short of naming which specific sibling tools consume app_id or any exclusion condition, so not a 5.

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