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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is fully covered. The description adds that the returned figure is composed of two components, the protocol margin and the pass-through card cost, which is real context. It says nothing about rounding, currency, precision, or how payee tier affects the take.

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?

A single front-loaded sentence with no filler; the core computation and its two components come first. Slightly parenthetical phrasing ("the take") costs a little clarity but no length.

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?

Placeholder.

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 0% and the description never mentions either parameter. It does not explain what minor units the amount is denominated in, nor what values payee_tier accepts (no enum), which is exactly the gap the description should close for a 2-parameter tool with an undocumented 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?

States a specific verb ("Compute") and a specific output (protocol margin/take plus pass-through card cost) for a settlement. The Viridis jargon is dense but the computation is identifiable, and none of the siblings (attestation, DID binding, certify, list modules, verify mark) overlap with toll computation, so no explicit differentiation is needed.

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?

There is no guidance on when to call this versus anything else, no prerequisites (does a settlement need to exist first?), and no statement about whether the result is advisory or authoritative. The agent must infer the usage context entirely from the name.

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