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

Annotations only declare readOnlyHint=false, so the description carries the real burden and does well: it discloses that tax is added to unit price, that instant fills avoid the listing fee, that auto_list incurs a 1% (or higher) fee, and that overflow goes to storage when cargo is full. It omits failure modes such as insufficient credits or order rejection, keeping 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?

Front-loaded with purpose, and every clause carries real information, but it is delivered as one long sentence with nested parentheticals (fees inside the instant-fill aside), which makes it harder to scan than a short bulleted split would 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 5-parameter mutating trade tool with no output schema, it covers cost model, delivery destination, and partial-fill handling, which is what an agent needs before calling it. Missing are credit/precondition checks and any hint of the result shape after a partial or failed fill.

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 already 100%, so baseline is 3, but the description adds genuine meaning: item_id also accepts an item name (e.g. 'Iron Ore'), while the schema only documents IDs, and it explains the price/fee consequences of auto_list and the cargo-vs-storage distinction for deliver_to beyond the enum text.

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: buying items at market price from the station exchange, with instant-fill semantics. That distinguishes it from create_buy_order and sell in substance, though no sibling is named explicitly, so the agent must infer the boundary itself.

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?

Gives conditional guidance for the two optional behaviors: use deliver_to=storage when sending straight to storage, and auto_list=true when unfilled quantity should become a buy order. It stops short of explicit 'use create_buy_order instead when...' routing, which is the main gap given how many order-related siblings exist.

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