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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower, yet the description adds real behavioral context beyond them: the pricing model ($0.04/call over x402), the prepaid x-credit-token header for unlimited calls, no free tier, and no API key required. It doesn't describe rate behavior or failure modes, but the added auth/billing disclosure is genuinely useful.

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-loads the core question and the mechanism before the Beryl timing specifics and billing details. Each sentence carries information, though the dense packing of dates, prices, and header mechanics makes it slightly heavy for a single-parameter read tool.

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?

An output schema exists, so return values need no explanation, and the description supplies the domain context an agent needs: what gets decoded, the post-Beryl finalization windows, and the billing/auth model. Complete for practical invocation, with only sibling routing left implicit.

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% for the single 'tx' parameter, so the schema already documents it as the withdrawal-initiation txHash. The description restates 'Required input: tx' without adding syntax or format meaning, which is exactly the baseline-3 case where structured data 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?

States a specific verb+resource: it decodes the L2ToL1MessagePasser event (withdrawalHash, target, value) from a Base withdrawal-initiation tx and estimates finalization windows. This is clearly distinct from generic siblings like base_tx, tx_decode, and bridge_status without opening any 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?

The opening question and 'Given a Base withdrawal-initiation tx' clearly establish when the tool applies, and 'For agents managing cross-chain liquidity' names the target user. However, it never names an alternative (e.g., bridge_status) or states when NOT to use it, so routing guidance is implied rather than explicit.

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