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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond annotations: it explains the returned recommendation, fallback, reset windows, rationale, weekly rotation, and source links, and it discloses that unknowns are labeled estimate or not published.

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 first sentence is front-loaded with the core behavior and return contents. The following sentences add useful qualifications and valid plan ids, though the plan-id list is long and makes the description dense; it earns its place by preventing invalid plan identifiers, but the structure could be cleaner.

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 output schema and a read-only annotation profile, the description does a good job explaining what is returned, including rationale, fallback, reset timing, and uncertainty labeling. The main omission is sibling differentiation, which matters because the sibling set contains several competing recommendation tools.

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 coverage is only 50%, so the description must carry some of the parameter burden. It usefully enumerates all valid plan ids, which the schema only illustrates with one example, but it does not add meaning beyond the schema for the task and state values, which remain defined primarily in the input schema.

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 uses a specific verb and resource: given owned plans, usage, and task type, it returns a recommended plan plus fallback and reset details. It is clear what the tool does, but it does not distinguish itself from recommendation-oriented siblings like pick_plan, recommend_plan, or can_afford_task.

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 implied by the input context (plans you own, usage states, task type), but there is no explicit when-to-use guidance, no when-not-to-use guidance, and no named alternative among the many similar sibling tools. An agent must infer that this is the routing/selection tool rather than a status or affordability tool.

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