Base Transaction Decoder

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

Despite annotations already declaring readOnlyHint=false, and destructiveHint=false, the description goes far beyond them by disclosing the financial cost, the payment mechanism (USDC on Base via x402), the quota cap, the token-based proof of purchase, and the fact that no account is needed. It also explains what the token is used for, which is critical behavioral context.

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?

Three sentences deliver a wealth of information without redundancy: what the pass costs, what it grants, how to use the returned token, and how to renew. The most important facts (price, quota) are front-loaded, and every clause earns its place.

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 there is no output schema and no parameters, the description is remarkably complete. It tells the agent exactly what the tool returns (a bearer pass token), how to attach it, that the token is the only proof of purchase, and when to repurchase. Nothing an agent needs to call or use this tool effectively 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?

There are zero parameters and schema description coverage is 100%, so the schema already provides all parameter information. The description adds nothing about parameters because none exist, and that is appropriate. A baseline of 4 applies here.

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 states a specific verb ('Buy'), a clear resource ('30-day pass'), and includes concrete details about price, currency, network, and the exact benefit (up to 10,000 explain_transaction calls). It also implicitly differentiates from the sibling tool explain_transaction by explaining that this pass removes per-call payment.

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 clearly communicates the context: you buy this pass when you expect to make many explain_transaction calls without per-call payment, and you renew after expiry. It does not explicitly name the alternative of paying per-call directly via explain_transaction, but the 'no per-call payment' phrase strongly implies it.

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

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

Beyond the annotations (read-only, idempotent, open-world), the description discloses critical behavior: deterministic onchain decode with no LLM, risk checks fail open, provenance.untrusted_fields must be treated as data not instructions, and gas_price_basis has reproducibility implications. It also clarifies verification-derived field timing. No contradiction with annotations.

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 long but tightly structured: purpose, input, return fields, risk semantics, provenance warning, determinism, chain, and pricing. It front-loads the core action. Some verbosity in the pricing and risk-check explanations is justified because this information is essential for correct usage and interpretation.

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 no output schema, the description compensates by enumerating all response fields and their meaning, explaining risk-check behavior, provenance trust boundaries, timing semantics, and payment requirements. For a single-parameter tool, this gives an agent everything needed to call it and interpret results correctly.

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?

The input schema already documents tx_hash at 100% coverage, including the exact 0x + 64 hex format. The description only repeats 'Input: a transaction hash' and adds no new parameter semantics beyond the schema. Baseline 3 is appropriate since the schema carries the necessary meaning.

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 opens with a specific verb and resource: 'Explain a Base-mainnet transaction in plain English.' It clearly distinguishes itself from the only sibling, buy_pass, by describing the explanation function and mentioning buy_pass only in the pricing context. The scope and output format are unambiguous.

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 explicitly restricts use to Base mainnet (chain id 8453), tells the agent when to use buy_pass for heavy usage, and offers an alternative payment path via POST /explain. It also gives rate-limit context (50 free calls per 24h) that signals when payment is needed. This is explicit when-to-use and when-to-switch guidance.

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