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

Annotations already declare this is a read-only, idempotent, non-destructive, non-open-world call. The description adds useful substance beyond that by enumerating the content domains returned (plans, prices, credit allowances, charging model, add-ons), which tells the agent what data it will get. It doesn't cover caching or freshness of pricing data, so it isn't a 5.

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 tight sentences: the first front-loads what is returned, the second gives the usage condition. No filler or redundancy.

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, the description compensates by listing the returned data categories, and the trivial one-parameter schema is fully documented. The only gap is any note on pricing freshness or whether the response is a single object versus a list, which is minor 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 coverage is 100% and the single enum parameter is fully documented in the schema ("Return only this plan. Omit for all plans."), so the description correctly does not need to restate it. Baseline 3 applies when the schema carries parameter meaning.

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 verb (Get) and resource (Mitosis plans/prices) and enumerates exactly what is returned: prices, credit allowances, usage charging, and add-ons. No sibling tool covers pricing, so explicit differentiation isn't needed, but it still clearly identifies the operation.

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 when comparing costs or recommending a plan" gives clear situational context for when to invoke it. It stops short of stating when not to use it or naming an alternative, but for a unique pricing tool that would be redundant.

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