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

The annotations already mark the tool as read-only and idempotent. The description adds useful behavioral context beyond that: account-tier limits (2 vs 5 plans), ranking by final value, and a single share_url opening all plans together. No contradiction with annotations.

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 with no filler. The key capability, constraints, and use case are front-loaded before any detail.

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 complex tool with nested settings and no output schema, the description plus the detailed input schema cover selection and invocation well. It doesn't spell out the response format, but 'rank by final value' and the schema's setting descriptions provide enough context.

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 top-level description adds little parameter-specific meaning, but the schema carries detailed descriptions for plans, include, and settings. At 50% schema description coverage, the missing as_of parameter is not addressed in the description, though the schema's existing field descriptions make the tool usable.

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 opens with a specific verb and resource: 'Run up to 5 plans over the same data and rank them by final value.' It clearly differentiates from siblings by focusing on multi-plan comparison and ranking, and it states the Pro limit.

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 to compare assets, cadences or start dates side by side' gives a clear intended scenario and contrasts with what a single-plan tool like run_dca would do. It doesn't explicitly name alternatives or list when not to use it, so it stops short of a 5.

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