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

With no annotations provided, the description alone must disclose behavioral traits. It indicates the tool returns a contract, and it lists specific components (top-up, ownership, amount, fee, replay, funding). However, it does not mention whether this is a read operation, if it requires any preconditions or authentication, or what happens if the contract does not exist. The description is adequate given the lack of annotations but could be more explicit about read-only behavior.

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 sentence that concisely lists the elements of the contract. It is front-loaded with the main verb "Return" and no extraneous information. It earns its place, though it could be slightly more polished.

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 0 parameters and no output schema, the description is the primary source of information. It covers the purpose and what the tool returns, but it does not clarify the context (e.g., when to use this over sibling tools, or how the returned contract might be used). It is complete enough for a minimal tool but lacks contextual guidance.

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?

The input schema has 0 parameters, so the description does not need to document any parameter behavior. Since schema coverage is 100% (there is nothing to cover), baseline is 4. The description adds value by explaining the specific nature of the contract, which goes beyond the empty schema.

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 states it returns a "separate direct x402 card top-up, active-card ownership, amount, fee, replay, and asynchronous funding contract," which clearly identifies the resource and what the tool does (return a contract). It distinguishes itself from sibling tools like get_card_contract and get_esim_contract by specifying the unique elements of this contract.

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 does not provide any guidance on when to use this tool versus other contract retrieval tools (e.g., get_card_contract, get_agent_contract). No context is given about prerequisites, conditions, or limitations, leaving the agent to guess based solely on the name and description.

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