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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds real value on top: the fixed one-cent-per-character pricing model and the explicit 'Does not send payment' clarification. It stops short of noting error behavior for unsupported rail/asset pairs or any rate limits.

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 compact sentences: purpose and cost first, then the return shape, then the side-effect disclaimer. No filler and the key facts are front-loaded.

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?

With no output schema, the description correctly covers the return shape (units, token, payout address) and confirms no payment is sent. Minor gaps remain around failure modes for invalid rail/asset combinations, but an agent has enough to call it correctly.

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%, so the baseline is 3, but the description goes further by giving concrete example values (rail=base, asset=USDC) that clarify the expected identifier format and by repeating the operational 20-800 char band tied to the pricing rule.

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+resource ('Get the exact amount to pay for a passage') with the pricing rule and what is returned. An agent can distinguish this quoting tool from read_passage and submit_paid_line without opening a schema.

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?

Makes the read-only quoting role explicit by stating 'Does not send payment', which implicitly routes payment to submit_paid_line, and the schema note points to read_spec for rail ids. It never states a when-to-use condition or explicitly names the alternative tool, so it falls short of full routing guidance.

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