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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered. The description adds genuine behavioral context beyond that: the computation formula, that an active transfer bonus is applied, and that cash fare and award fees must share a currency. It does not say what the response looks like or how options map to results, so it is good but not rich.

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?

Front-loads the formula and what is returned, then the transfer case, then the call-to-action. Dense but every sentence carries information; only the closing 'rather than doing the maths yourself' is slightly redundant.

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?

No output schema exists, but the formula tells the agent the result is a per-point value in cents, which is the key missing piece. For a 4-parameter computation tool with mostly documented schema, this is nearly complete; only the response shape per option is unstated.

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 75%, and the description adds meaning the schema cannot: the bank+program pairing drives a transfer-ratio lookup with a concrete example (Belgian Amex to Flying Blue 2:1) plus active bonuses, and it explains the value is judged per bank point spent. That clarifies the most complex parameter relationship, though it leaves bank_points override and miles_earned_paying_cash to 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?

States a precise verb-and-output: it computes exact cents-per-point for an award versus the cash fare, and even gives the formula. An agent can immediately tell this apart from award_chart (chart lookup), transfer_options (ratio lookup) and cashback_cards, since the transfer handling is folded into this tool.

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?

Explicitly tells the agent to call it for every award compared rather than doing the maths manually, and gives a conditional instruction for transfer-paid awards (pass bank + program). It does not name siblings or state when-not to use it, so it falls short of a 5.

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