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

Annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false) only sketch the safety profile, and the description adds substantial context beyond them: the 403 destination_not_authorized enforcement, the chain-specific signing artifacts (EIP-712 typedData on EVM, never-landing memo proofTransaction for Ledger on Solana), and an explicit human-confirmation requirement. This is exactly the behavioral detail annotations cannot carry.

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?

It is a dense, run-on paragraph but every clause earns its place – the 403 trigger, the return shape, the per-chain signing path, and the confirmation rule. It is front-loaded with the lock behavior before the signing steps. Slightly overpacked, but not padded.

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?

No output schema exists, yet the description fully describes the return values ({nonce, message, expiresAt}, typedData, proofTransaction) and the complete downstream signing flow. For a complex, multi-step, safety-critical authorization tool, nothing an agent needs to call it correctly is missing.

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 wallet, chainId and receiver are already documented in the schema, and the description adds no syntax or format detail beyond it. It does contextualize the parameters by explaining the EVM vs Solana (chainId) branching and stressing that the full receiver address matters, but that is largely behavioral rather than semantic. Baseline 3 applies when the schema does the heavy lifting.

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?

Although it opens with the terse label 'Destination lock,' the description immediately states the concrete effect: a receiver different from the signing wallet is refused by swap_build, double_build and nn_build (403 destination_not_authorized) until authorized. It names the sibling tools and the exact return payload ({nonce, message, expiresAt}, plus typedData/proofTransaction), so an agent can distinguish it from destination_authorize without opening a schema.

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?

Explicit routing: sign via prepare_signing (EVM) or wallet message (Solana), then 'call destination_authorize.' It also gives clear when-not guidance: 'Never sign this without the user asking to send to that address. Paying an invoice does not need it.' Both the alternative tool and the exclusion condition are stated.

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