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

With no annotations, the description carries full burden. It discloses server-side signing, EIP-191 format, output as 65-byte hex, and that no transaction occurs. It does not discuss idempotency, rate limits, or authentication, but these are reasonable for a signing tool. The transparency is strong but not exhaustive.

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?

Three sentences, front-loaded with purpose, no unnecessary words. Every sentence adds value: action, output format, and key behavioral note.

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 two parameters with full schema coverage, no output schema, and no annotations, the description is complete. It explains input encoding, output format, and side-effect (no transaction), which is all the agent needs to select and invoke 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 coverage is 100%, but the description adds meaningful context: it clarifies that message is UTF-8 by default and provides the hex encoding option for raw bytes with the expected format ('0x-prefixed'), going beyond the schema's brief descriptions.

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 verb 'sign', the resource 'message', and the standard 'EIP-191 (personal_sign)', distinguishing it from sibling tools like fuse_sign_typed_data and fuse_send_native (which submit transactions). It also specifies the output format (65-byte hex signature).

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 explicitly states 'No on-chain transaction is submitted', implying it is for off-chain signing. It does not explicitly mention when not to use it or suggest alternatives like fuse_sign_typed_data for typed data signing, leaving the agent to infer from sibling names.

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