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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds no behavioral context beyond the purpose sentence: it doesn't say what the tool returns (MER value, over-claim percentage) or the units/assumptions used, and the second sentence is a promotional link rather than disclosure.

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 compact and front-loads the purpose, but the second sentence is an external URL plug that consumes space without helping an agent decide or invoke. Trimming it would leave a tight, useful description.

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 three-required-parameter calculator with no output schema, the description should ideally indicate what comes back (a MER figure and an over-claim delta). It covers the core comparison but leaves the return semantics to inference.

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 description coverage is 100%, so all three parameters (totalRevenue, totalSpend, platformRoas) are already documented with units and source guidance. The description adds no further semantic detail, which is acceptable but warrants only the baseline score.

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?

States a specific verb and resource: compare platform-reported ROAS against blended MER to quantify pixel over-claim. It is distinguishable from the sibling roas_calculator, though the relationship to other attribution tools (e.g., post_ios14_blended_attribution_modeler) is not spelled out.

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?

No indication of when to reach for this tool versus the many sibling calculators (roas_calculator, cpa_to_cac_scalability_matrix, post_ios14_blended_attribution_modeler). It also doesn't mention prerequisites such as needing backend/store revenue rather than platform revenue.

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