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

With no annotations, the description carries the full burden and does well: it discloses the exact price and payment rail ($0.01 USDC on Solana per quote), that the quote is signed, and what it contains. It omits failure/refund behavior if the payment succeeds but the quote cannot be produced, which keeps it from 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?

It is a single dense sentence that front-loads the cost and then the deliverable, with no filler. The run-on punctuation (colons, parenthetical) makes it slightly harder to parse than it needs to be.

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 one-parameter, nested-input tool with no output schema, the description compensates by enumerating the return contents (each fee leg, all-in total, source and vintage) and the payment requirement. Only error and idempotency behavior remain unaddressed.

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 nested object already documents seller_price_micro, facilitator, scheme, and the facilitator position inputs, so the baseline is 3. The description adds only the framing that position inputs are conditional on the fee model needing them, which is useful but largely restates the 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?

The description states a specific verb and resource: it returns (buys) one signed true-cost quote covering fee legs, all-in total, and model source/vintage for a submitted price, facilitator, and scheme. That clearly separates it from sibling criteria/precheck tools, though it never names them explicitly.

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?

Usage is implied by the described input shape (price + facilitator + scheme) and the note about CDP past the free tier, so an agent can infer when this is the right call. There is no explicit when-not guidance and no named alternative such as fee_oracle_recipe or fees_estimate.

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