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

Annotations already flag destructiveHint=true, but the description adds substantial context beyond them: the offer closes to new fills while already-executed fills remain completed purchases, the two-phase confirm=false/confirm=true flow, and the auth requirement. This is exactly the information an agent needs before committing an irreversible action.

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?

Five short sentences, each doing distinct work: trigger examples, effect, irreversibility caveat, sibling disambiguation, two-phase protocol, auth. Zero filler and correctly 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?

For a destructive two-parameter mutation with an output schema and destructive annotation, the description covers the effect, what is not undone, auth, disambiguation, and the preview path. Nothing an agent needs to invoke it safely is missing.

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% and the schema itself documents confirm's preview/commit semantics and the open_offer_id source (list_my_open_offers). The description's 'confirm=false previews, confirm=true commits' restates the schema rather than adding new parameter meaning, 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 ('cancel ... open offer resting on the XP marketplace') and explicitly distinguishes it from the sibling cancel_my_offer for single-listing offers. An agent can select this without opening the 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?

Front-loads the triggering condition with realistic user phrasings ('cancel that open offer for tickets to the game') and names the alternative (cancel_my_offer) with the exact condition that selects it. No inference required.

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