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

The description adds meaningful behavioral information beyond the annotations by explicitly stating 'Never signs or broadcasts.' This tells the agent that the preparation is non-final and side-effect-free at execution level, which is more specific than the generic readOnlyHint annotation.

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 short sentences with no filler. The primary purpose is front-loaded and the behavioral constraint is delivered immediately after, making the entire definition highly scannable 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 simple three-parameter tool with a complete schema and an output schema present, the description covers all necessary caller-facing behavior: what is prepared and what is not. It could add a bit more context about what the returned prepared artifact is, but the output schema and annotations carry the remainder of the burden.

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 the input schema already fully documents from, to, and tokenId. The description adds no additional parameter-level meaning, but none is needed given the complete schema coverage.

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 uses a specific verb and resource ('Prepare a direct NFH transfer') and adds a crucial caveat ('Never signs or broadcasts') that distinguishes it from any tool that would execute or submit a transfer. Despite many prepare_* siblings, the combination of 'direct NFH transfer' and the no-sign/no-broadcast constraint makes the purpose 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 clearly states this is for preparing a direct NFH transfer to another address, which gives the agent a concrete use context. It does not explicitly name alternative tools or list when-not-to-use cases, but the domain is simple enough that the intended usage is clear without exclusions.

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