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

Annotations already declare readOnlyHint/idempotentHint/openWorldHint, so the bar is lower, yet the description adds real behavioral context the annotations cannot: visibility is permission-dependent ('Non-owners see active included streams only') and it states what it does not do (no posts, no subscription). It stops short of describing auth requirements or error/pagination 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 short sentences, front-loaded with what is returned, then the visibility rule, then the exclusions. No filler, and each clause carries distinct information.

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 one-parameter, read-only tool with a full output schema and rich annotations, the description covers purpose, visibility nuance, and scope boundaries. The return shape is covered by the output schema, so the only minor gap is any auth/error context, which is not critical here.

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 single 'id' param already documents its source (list_stream_packages or list_my_stream_packages). The description adds no parameter-level meaning 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?

Specific verb+resource: 'Read a stream package, its available prices, and included stream cards,' enumerating the returned content. The closing clause 'Does not return stream posts or subscribe to the package' explicitly separates it from get_stream_posts and the *stream_subscription tools, so an agent can tell it apart from siblings without opening schemas.

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?

Usage is only implied by the required 'id' and by the negative clause 'Does not return stream posts or subscribe to the package,' which is a weak when-not rather than a routing rule. It never says when to pick this over get_stream, get_stream_package_subscription, or list_stream_packages, so the agent must infer.

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