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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds valuable context: the cost ($0.001 USDC per call), the exact equivalence to a specific GET endpoint, and the ordering/volume details. These go beyond the annotations and help the agent anticipate behavior, though rate limits or error handling are not mentioned.

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 two sentences with zero redundancy. The core purpose is front-loaded, followed by cost and API equivalence. Every word earns its place, making it easy for an agent to parse quickly.

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 the tool has an output schema, return format is covered. The description communicates cost, supported granularities, ordering, and volume, which are the key operational details for a read-only, idempotent call. It lacks mention of authentication or rate limits, but these are likely inferred from the venue and annotations. Overall, it's complete for the tool's complexity.

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 provides 100% coverage with descriptive text for all three parameters (limit, product, granularity), so the baseline is 3. The description adds the granularity range ('1m to 1d') which clarifies allowed values beyond the schema's vague 'candle width in seconds', but it does not meaningfully explain the 'limit' format or other nuances. Thus, it offers only a slight enhancement over 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?

The description clearly states that the tool returns candles from Coinbase Exchange, specifying the granularity range (1m to 1d), ordering (oldest first), and inclusion of volume per bucket. It distinguishes itself from other exchange-specific candle tools by naming the venue, and the title adds 'OHLC' clarity. This is a specific verb+resource definition.

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 notes the supported granularities and the cost per call, which imply when this tool is appropriate (e.g., for Coinbase data with standard granularities). However, it does not explicitly compare against alternative candle tools (like market_kraken_ohlc or market_okx_candles) or state when not to use it. The 'byte-identical' reference gives a sense of exactness but no routing guidance.

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