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

The description discloses key behavioral traits beyond annotations: the two-step payment protocol ('first call returns paymentRequired; retry with the same arguments plus paymentPayload'), the need for coin IDs rather than tickers, and the indicative pricing model. It also clarifies data source (CoinGecko) and that no account is needed, adding significant context beyond the readOnlyHint annotation.

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 well-structured with a clear front-loaded overview, bulleted action list with prices and parameters, and a separate payment flow explanation. Every sentence adds value, and the length is justified by the tool's complexity (six actions, 16 params, payment protocol). No fluff or repetition.

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 tool's complexity and the presence of an output schema, the description is complete: it covers all six actions, their parameters, defaults, required vs optional, pricing, the payment challenge flow, and important usage notes (e.g., search-first workflow, ID not ticker). It also acknowledges that exact charges come from the live challenge, which is essential for correct invocation.

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 schema already has 100% parameter descriptions, but the description adds action-level parameter semantics: it groups parameters by action, states which are required (q, ids, id, tokens), gives examples ('bitcoin'), and clarifies defaults and constraints (e.g., 'limit 1-250, default 100'). This goes beyond the schema, though some information is redundant with schema descriptions.

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 clearly states 'Crypto market-data lookups (CoinGecko-sourced pricing and market data)' and enumerates six specific operations (search, price_feed, market_data, historical_data, trending, token_prices). This specific verb+resource combination distinguishes it from sibling tools like network.token_price by highlighting its multi-action, CoinGecko-sourced, pay-per-call nature.

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 provides detailed guidance for when to use each action, such as 'Call this first to resolve a coin id before using price_feed or historical_data' and 'use for "top N coins" / market overview questions'. It explains selection criteria, required parameters, and the payment flow. However, it does not explicitly mention alternative sibling tools or when not to use this tool, so it falls short of full cross-tool differentiation.

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