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

Anotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, and the description adds genuine behavioral context beyond that: the Beryl upgrade timing (7-day to 5-day window, dual-proof fast path at ~1 day), the event-decoding mechanism, and the cost/auth profile ($0.04/call over x402, prepaid x-credit-token header, 1 free call/day, no wallet or API key). This is material, non-redundant behavioral disclosure.

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: the first sentence states the core question and rules, then mechanism, audience, input, pricing, and auth follow in order. Each sentence carries distinct information, though the pricing sentence is longer than strictly necessary and could be trimmed without losing meaning.

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?

With an output schema present, the description needn't explain return values, and it covers purpose, mechanism, temporal rules (Beryl date of 2026-06-25), the single required input, pricing, and authentication prerequisites. The only minor gap is guidance on invalid txs or edge cases, but for a one-param read-only tool this is near-complete.

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% — the tx parameter is described as 'Base withdrawal-initiation txHash' — so baseline 3 applies. The description echoes 'Required input: tx' and 'Base withdrawal-initiation tx' but adds no format, encoding, or validation detail beyond what the schema already provides.

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 verb-resource pair: it 'decodes the L2ToL1MessagePasser event (the withdrawalHash, target & value needed to prove/finalize on L1) and estimates the finalization windows' from a 'Base withdrawal-initiation tx'. This is clearly distinct from siblings like base_tx or tx_decode, and it states the concrete outputs an agent will receive.

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 description frames the use case with 'When can a Base→L1 withdrawal be finalized?' and scopes it 'For agents managing cross-chain liquidity', giving implied context for when to call it. However, it never names sibling alternatives (base_tx, base_receipt, tx_decode) or states when NOT to use this tool, leaving the selection logic largely to inference.

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