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

Annotations already cover read-only, idempotent, non-destructive and closed-world. The description adds real value beyond them: 'Nothing is stored', 'Amounts in pounds', and an assurance the result matches the website planner exactly, which tells an agent the output is deterministic and canonical.

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?

Two sentences, front-loaded with the tool's payoff and then the guarantee about storage and currency. No filler, though the phrasing of the first sentence is slightly awkward to parse.

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 does the work of explaining return content: the winning order, dates, and residual money after costs. Combined with the strong input schema, an agent has enough to call this 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 86%, so almost every parameter is already documented. The description only contributes unit context ('Amounts in pounds') and hints at the buffer concept via 'what is left after costs', leaving the baseline score appropriate.

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 concrete outcome: which offers fit a situation, ranked by payout, with dates and net-of-cost amounts. That is specific enough to distinguish it from list_offers and get_offer, though it never names those siblings 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?

Calling it a 'quick check' and tying it to the pocketly.co.uk/check planner implies when to use it, but there is no explicit when-not-to-use guidance or named alternative for browsing offers versus evaluating them.

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