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

No annotations are provided, so the description carries full responsibility. It discloses a key behavioral trait: the tool only 'prepares an unsigned transaction payload,' not a direct execution. It also states the requirement for buyer wallet signature. However, it omits details about error cases, response format, or what happens after signing. Given zero annotation support, a 3 is appropriate – it provides some behavioral context but not comprehensive.

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?

The description is a single, front-loaded sentence that states the purpose and the key prerequisite. Zero wasted words; every element adds value.

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?

Given the low complexity (2 parameters, no output schema), the description covers the essential facts: what the tool does, that it produces an unsigned payload, and the required signature. It could specify the return format or next steps more explicitly, but the core usage is adequately covered for an agent to invoke it 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 description coverage is 100% with both parameters ('domainName' and 'buyerAddress') already described. The description adds the contextual note that a buyer wallet signature is required, which loosely relates to buyerAddress but does not add new semantic meaning beyond the schema. Baseline 3 is correct when schema fully documents parameters.

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 clearly states a specific action: 'cancel an active marketplace offer.' It also specifies the output is an 'unsigned transaction payload,' which distinguishes it from sibling tools like marketplace_accept_offer (accepting) and marketplace_cancel_listing (canceling a listing). The verb and resource are unambiguous.

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?

The description provides clear context for when to use this tool (to cancel an offer) and notes the prerequisite of the buyer's wallet signature. However, it does not explicitly mention alternative tools or when NOT to use it. The sibling list implies differentiation, but the description itself lacks explicit exclusions.

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