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

Annotations already declare readOnly=true, idempotent=true, non-destructive, so the safety profile is covered. The description adds real value beyond that: it confirms no signing/paying occurs, guarantees the recipient receives exactly `amount` at their own address, and describes the two-step GET-with-signature flow. It does not discuss rate limits or failure modes.

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?

Four tight sentences, each earning its place: what is returned, how to pay it, the amount guarantee, and the scope disclaimer. Front-loaded with the return payload, with no filler.

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?

Output schema exists so return shape need not be explained, yet the description still summarizes the key payload components helpfully. For a read-only preparation tool with a well-documented schema, nothing an agent needs to invoke 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 coverage is 100%, so the baseline is 3, but the description adds meaning by clarifying that `amount` is what the caller RECEIVES on the destination (not what they pay), which is a critical semantic distinction for a bridge tool. It mentions payTo and EIP-712 domain context without repeating schema text.

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 (prepare) and resource (bridge payment) and describes precisely what is returned: the x402 payment request fields (network, asset, payTo, amount, EIP-712 domain) plus the URL to call. This is clearly distinguishable from siblings like bridge_quote or bridge_routes.

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?

Gives explicit usage context: pay it with your own x402 client, sign one EIP-3009 authorization, repeat the GET with the PAYMENT-SIGNATURE header. It also states the negative boundary ('This tool does not pay or sign anything'). It stops short of naming which sibling to use for quoting or route discovery first.

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