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

Annotations declare readOnly/idempotent/non-destructive, but the description adds substantial context the annotations cannot convey: the x402 pricing model ($0.02/call on Base), the prepaid x-credit-token header option, the 1 free call/day allowance, and the custody guarantee ('we never hold keys'). The quote-not-execute framing also reconciles why readOnlyHint=true despite returning a tx. No annotation contradiction.

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?

Front-loaded with the core purpose and return contents, then chains, tokens, execution caveat, and pricing in a logical order. A few phrases are filler ('Not financial advice', the 'Agents bridge across chains and get it wrong' framing), but most sentences carry operational 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 read-only quoting tool with an output schema already describing return values, the description covers everything an agent needs: supported chains, token input formats, required inputs, pricing/auth model, and the execution caveat. Nothing material 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 baseline is 3, but the description adds real meaning beyond the schema's terse 'From chain'/'To chain'/'Amount to bridge': it enumerates valid chains (ethereum, base, arbitrum, optimism, polygon) and token formats (USDC/USDT/ETH/WETH/DAI symbols or a 0x address with amountUnits). That is genuine value the schema does not provide.

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+resource (returns the best cross-chain route via the LiFi aggregator) and enumerates the concrete outputs: which bridge, arrival amount, est. time, gas + bridge fees in USD, and a ready-to-send tx. This scope is distinguishable from siblings like bridge_status (tracking) and fresh_bridge without opening either 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?

Gives clear context for use (bridging across chains when routing quality and fee safety matter) plus an explicit operational caveat: it is a quote, so re-quote with your own sender before executing. It does not name alternative sibling tools or state exclusions, so it stops short of a 5.

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