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

Annotations already declare readOnlyHint=true and idempotentHint=true. The description adds value by disclosing that the tool is free, reports all problems at once rather than just the first, and lists the specific outputs (adjustments, flat price, balance shortfall). This explains behavioral traits beyond the annotations without contradicting them.

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 two sentences, front-loaded with the key purpose ('Checks a campaign BEFORE launching it'), and every phrase earns its place. The parameter caution and usage directive are concise and actionable, with no fluff 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?

This is a complex tool with 11 parameters, but the schema provides full coverage. The description covers the tool's purpose, when to use it, and a critical parameter misuse caution. Combined with the annotations (read-only, idempotent) and the output schema (present), the description is complete enough for an agent to call it correctly without additional clarification.

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 all parameters have descriptions. The description's note about passing cohortSize instead of addresses merely repeats the schema's existing 'The number, not the addresses' for that parameter. No new semantic meaning is added beyond the schema, so the baseline of 3 is appropriate.

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 clearly states the tool checks a campaign before launch, enumerating the specific outputs (problems, adjustments, price, balance coverage). It distinguishes itself from launch_campaign by saying 'Always quote before launch_campaign,' but it does not explicitly differentiate from the sibling validate_campaign. Overall, the purpose is clear and specific, though sibling differentiation is implicit rather than explicit.

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 gives explicit usage guidance: 'Always quote before launch_campaign' provides a clear when-to-use directive. It also includes a specific parameter caution ('For targeted campaigns pass cohortSize (the number of people), never the addresses'), which prevents misuse. This is strong, actionable guidance that goes beyond the schema.

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