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

Beyond the annotations (readOnlyHint=true, idempotentHint=true, destructiveHint=false), the description adds critical details like caching (~1800s), auth methods (X-Api-Key or x402), cost ($0.001 USDC per call), rate limit (60/min), and that it is billing, not a side effect. No contradictions 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 well-structured with clear sections (Purpose, Behavior, Auth, etc.) and front-loaded with the key action. It is somewhat verbose but every sentence adds value, especially given the complexity of billing and auth. Minor redundancy (Purpose repeated twice) prevents a 5.

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 2 parameters (100% coverage) and the existence of an output schema, the description covers all aspects: behavior, auth, cost, rate limit, return summary ('Per-symbol funding rate data with exchange-level breakdowns and predicted next funding'), and usage context. No gaps.

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 parameters. The description adds value by clarifying that the optional symbol defaults to 'all major' and explaining the __x_payment parameter's role in retry scenarios, which is not in the schema's description but aligns with it.

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 explicitly states it provides 'Current and predicted perpetual futures funding rates across all major exchanges via Coinglass with 30-min cache'. The verb 'call' and resource 'funding rates' are specific, and the scope (all major exchanges) is clear. It distinguishes itself from siblings like cc.agent_strategy by suggesting pairing.

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 provides explicit guidelines: 'Use for research / signal context. Pair with cc.agent_strategy (paper) before any live order. Do not invent fills from this data alone.' This tells when to use and when not to, with a clear alternative mentioned.

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