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

Beyond the annotations, the description discloses that the tool never signs or submits, returns only source-chain steps, cannot guarantee single execution due to nonce boundaries, and issues envelopes valid for 300 seconds after which the verifier rejects them. These are material behavioral caveats that align with readOnlyHint=true and idempotentHint=false.

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?

The description is dense and front-loaded with the core action, and the later sentences add necessary constraints and caveats rather than filler. It is longer than minimal but appropriate for a high-risk bridging operation; only slight redundancy around valid_until/stale-envelope exists.

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 the nine parameters, nested objects, safety annotations, and an output schema, the description covers the essential operational context: route set, chain/token refusal, EOA/Safe recipient behavior, non-execution guarantee, replay risk, and envelope freshness. Nothing critical is left unexplained for a caller to safely request a bridge construction.

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?

With only 44% schema coverage, the description compensates by clarifying that tokens are native USDC, amounts are exact gross atomic units, chains are restricted to the enumerated set, and destinationRecipient is optional for EOAs but required for Safes. Some params still rely on schema names, but the key non-obvious meanings are covered.

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 names a specific action ('Prepare, decode, and verify') on a specific resource ('unsigned cross-chain native-USDC bridge construction aid') and bounds it to the v1 Circle-CCTP route set. It also states the concrete deliverable (ordered allowance-reset, approval, and call steps on the source chain), making it easy to distinguish from the swap/perp prepare siblings.

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?

It gives clear eligibility signals: caller-owned EOA or Safe, native USDC only, only the five listed chains, and explicitly refuses any other chain/token/bridge route. It does not, however, point to a sibling tool for out-of-scope cases, so the when-not guidance is complete but alternative routing is left to the agent.

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