build_userop

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

With no annotations, the description discloses key behaviors: it returns sender, nonce, callData, buildId, and notes that platform fills gas/paymaster fields. However, it omits details like authorization requirements, side effects, or rate limits. It does not contradict any annotations.

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?

Two sentences, no fluff. First sentence states purpose and returns, second adds behavioral context. Information is front-loaded and efficient.

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 tool with 11 parameters and no output schema, the description is minimal. It does not explain the workflow sequence (e.g., that buildId is used in later signing steps) or relationship to sibling tools like 'sign_userop'. Adequate but lacks context for the overall process.

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%, so baseline is 3. The description adds no additional meaning to parameters beyond the schema, which already provides adequate descriptions. No parameter elaboration is needed.

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 the tool builds an unsigned ERC-4337 UserOperation from a transaction request, specifying the verb 'Build' and the resource 'unsigned ERC-4337 UserOperation'. It distinguishes from siblings like 'sign_userop' (signing) and 'send_batch' (sending).

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 implies usage as a preliminary step before signing, but does not explicitly state when to use it versus alternatives, nor does it provide when-not-to-use guidance. It mentions platform fills gas/paymaster fields before signing, but lacks explicit recommendations.

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