buy_passBuy a 30-day pass for $9 in USDC on Base via x402: up to 10,000 explain_transaction calls with no per-call payment. Returns a bearer pass token; attach it at _meta["btx/pass"] on MCP calls or as the X-BTX-Pass header on POST /explain. No account; the token is the only proof of purchase. Renew by buying a new pass after expiry.
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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.
Add one secure layer between your agents and this server.
buy_pass and explain_transaction are completely distinct in purpose, inputs, and outputs. There is no overlap or plausible confusion between purchasing access and decoding a transaction.
Both tools follow a consistent lower_snake_case verb_noun pattern: buy_pass and explain_transaction. The names clearly indicate the action and object, with no mixed conventions or vague single-word names.
Two tools is on the low side and falls into the borderline 'feels thin' range. However, the narrow single-purpose decode domain and the auxiliary pass-purchase tool make the count borderline but still coherent.
The core decode workflow is fully covered: a transaction hash produces a thorough explanation including assets, counterparties, risk flags, gas, status, and provenance. Since this is a read-only explainer, there is no update/delete lifecycle, and the tool surface has no obvious dead ends.