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

Annotations already declare readOnlyHint: true, idempotentHint: true, and destructiveHint: false. The description only repeats the read-only aspect ('Side effects: none (read-only)') without adding any new behavioral context such as authentication requirements, rate limits, or error behavior. With annotations present, the description adds no value beyond a redundant statement, so the score is low.

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 extremely concise: one purpose sentence plus a side-effect note. It is front-loaded with the core purpose, contains no fluff, and every word earns its place. The structure is optimal for a simple read-only tool.

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 optional parameter, no required fields), the presence of an output schema, and annotations covering safety, the description is largely complete. It states the purpose and side effects. Minor gaps include not mentioning potential error conditions or the behavior when the user_id is invalid, but these are not critical for a read-only informational tool with schema-defined outputs.

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 single parameter user_id has full schema description coverage (100%) with a clear explanation and default. The tool description does not mention parameters at all, but since the schema already documents them completely, the description doesn't need to compensate. The baseline of 3 applies because the schema does the heavy lifting.

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 states a specific action ('Get') and resource ('plan'), and specifies the returned information (plan type, admin/owner flags). It is clear and unambiguous, though it doesn't explicitly distinguish from sibling tools like get-user or get-token-info. The purpose is evident enough for an agent to select it when plan information is needed.

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 provides no guidance on when to use this tool versus alternatives. There are many get-* sibling tools, and no mention of conditions under which this tool is preferred (e.g., when needing plan-specific data vs. general user details). No exclusions or alternative recommendations are given, leaving the agent to infer context from the name and parameter.

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