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

Adds substantial behavior beyond the readOnly and openWorld annotations: fallback to Kraken or Bitstamp when Coinbase is rate-limited, the source field identifying the venue, pricing per successful call, and no charge on failure. These are important operational details for an agent.

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 purpose and key constraints, then covers fallback behavior and pricing. The disclaimer is minor boilerplate, but otherwise the description is efficient and well-structured.

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 that an output schema exists and all parameters are documented in the schema, the description covers everything an agent needs: data source, fallback behavior, ordering, limits, pricing, and charging policy.

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%, so the schema already documents pair, limit, and granularity including defaults. The description reinforces granularity options and the 300-candle limit but does not add syntax or format details beyond the schema.

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 the exact resource (OHLCV candles), the venue (Coinbase Exchange public market data), supported pairs and granularities, and ordering. This clearly distinguishes it from sibling tools like crypto_price, crypto_orderbook, and crypto_indicators.

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?

Provides clear context for when the tool applies: Coinbase trading pairs, specific granularities, and a maximum of 300 newest-first candles. It does not explicitly name alternatives or exclusions, but the scope is clear enough to guide selection.

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