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

No annotations, so the description carries full burden. It discloses a real financial side effect (price plus refundable collateral debited from funded balance) and states the exact amount is returned in the reply, which is valuable behavioral context. It doesn't explain refund mechanics, failure/escrow behavior, or rate limits, 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?

Four tight sentences front-loaded with the step role and primary purpose. The credential/parameter sentence is compact and every clause carries distinct information.

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?

Covers the action, prerequisites, cost model, and required credentials for a state-changing tool with no annotations and no output schema. Missing only edge-case behavior (collateral refund timing, failure handling, task_payload schema) to be fully complete.

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 only 17%, so the description must compensate. It identifies agent_id, api_key, service_id, and task_payload, and clarifies api_key's origin (marketplace_register). It doesn't explain task_payload structure, trade_type semantics (already in schema), or deadline_hours, leaving a gap for a 6-param tool.

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 ('Order a service') and explicitly anchors it to a sibling tool ('found in marketplace_services') that must be used first. An agent can distinguish this from marketplace_publish_service or marketplace_accept_contract without opening schemas.

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?

Describes the buyer-side workflow step ('Buyer step') and points to marketplace_services as the discovery prerequisite, and to marketplace_register as the source of credentials. However, it doesn't state what to do on failure or mention alternative buyer paths, so it stops short of full when/when-not guidance.

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