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

Annotations already declare destructiveHint=true and non-idempotent, so the description is not carrying the safety burden alone — but it still adds real value: it spends CWM, consumes cargo space, returns amount bought and total cost, and cannot be undone, with selling back only at sell price minus taxes and fees. It stops short of saying what happens if stock or cargo space is insufficient for the full quantity (partial fill vs. rejection), which is the main remaining ambiguity for a destructive trade.

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?

Six short sentences, front-loaded with the action and the docked precondition, then alternatives, then effects. Dense but every sentence carries either routing or consequence information; the closing taxes-and-fees remark is the only slightly peripheral detail.

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, and the description compensates by stating the return payload (amount bought and total cost). Combined with stated costs, cargo consumption and irreversibility, an agent has nearly everything needed; the unstated partial-fill/insufficient-funds behavior is the only notable gap.

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 100%, so item_code, quantity and bearer are already fully documented including the CWM/cargo/stock limits. The description adds only ambient context ('at the current price') and no additional parameter-level syntax or format guidance, so baseline 3 applies.

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 and resource ('Buy goods instantly from the station market at the current price') and immediately differentiates itself from two siblings by naming a market-order execution semantic. An agent can distinguish buy from estimate_purchase and place_orders without opening any 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?

Explicitly routes the agent: use estimate_purchase to check price first, use place_orders (type BUY) for a limit order, use this tool for an immediate market fill. It also states the precondition 'Ship must be docked', so both the when and the prerequisite are covered.

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