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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description still adds value by asserting no subscription is created and no charge occurs, which is a business-level side-effect guarantee annotations cannot express, though it omits pagination/result-size behavior.

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: scope first, then routing to alternatives, then the negative side-effect statement. No redundant restatement of the title or schema content.

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 an output schema present, return values need no explanation, and the schema covers pagination via limit/nextToken. The description covers scope, alternatives, and non-effects, so an agent has what it needs; only pagination behavior is left entirely to the schema.

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 description coverage is 100% and the enum meanings for queryType and streamPackageCategory are fully documented in the schema itself. The description adds no parameter syntax or semantics beyond that, so the baseline 3 applies.

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 (List), resource (stream packages), and scope (CREATED or SUBSCRIBED by the signed-in user), plus the extra payload (available prices). This clearly differentiates it from list_stream_packages (all packages) and the subscription-status siblings.

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?

Names both alternatives explicitly with their selection conditions: list_stream_packages for browsing all packages, get_stream_package_subscription for billing status. It also states a negative ('Does not create a subscription or charge the user'), leaving nothing to inference.

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