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

With no annotations, the description carries the burden and does well: it discloses the return value (a Sign-In with Ethereum message), the signing method, the 10-minute time bound, and that the server handles no keys. It does not state error behavior or what happens after expiration, but the core behavioral contract is present.

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 front-loaded sentences that lead with 'Step 1', then the return value, then the handoff instructions. No filler; every clause carries actionable information.

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 two-parameter, no-output-schema preparation tool, the description supplies the flow (message -> sign -> login), the timing constraint, and the security note about keys. The only meaningful gap is the undocumented chainId parameter.

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 only 50%: walletAddress is documented in the schema, but chainId has no description anywhere. The description implies the wallet context ('from the given wallet') but never explains chainId or its defaults, so it does not fully compensate for the coverage gap.

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?

States a specific verb and resource ('Step 1 of signing in to Mercadopleis') and clarifies the downstream purpose (register orders, message seller, download deliverables). It also distinguishes itself from the sibling login tool by positioning itself as the prerequisite step that produces the message login consumes.

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?

Explicitly frames this as step 1 and names the next tool (login) and the exact handoff: sign with personal_sign (EIP-191) and pass the signature to login within 10 minutes. The 10-minute expiry and the 'no keys needed by this server' note give the agent clear operating conditions.

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