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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so safety is covered. The description adds meaningful behavioral context beyond annotations: default slippage assumptions (0.2% taker, 0.1% maker), the taker/maker1/maker2 mode distinction, and pricing ($0.001/call or Carry key). It still does not cover auth requirements, rate limits, or output format details.

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 compact and front-loaded: it leads with the three computed outputs, then states modes, defaults, pricing, and intended use. Every clause carries information relevant to invocation, with no wasted prose.

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?

With rich safety annotations and no output schema, the description carries the burden of explaining returns and behavior. It names the three return metrics, default slippage values, mode options, and pricing, which is enough to invoke the tool with only the required spread_apr. The remaining gap is the unexplained lev parameter and lack of return-format detail, which are minor.

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 description coverage is only 20%, so the description must compensate for the four undocumented parameters. It adds semantics for mode (taker/maker1/maker2) and for slippage via default values (0.2% taker, 0.1% maker), but it never explains the lev parameter or its role in net return on margin. This is partial compensation, not full coverage.

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 computational purpose: round-trip cost, break-even days, and net return on margin for a funding spread. It names the modes and slippage assumptions, so an agent can identify it as a fees/slippage break-even calculator. However, it does not explicitly distinguish itself from sibling carry_* tools, leaving sibling routing to inference.

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 final sentence, 'Use to compute fees/slippage break-even for a funding spread,' gives an explicit use case. But it offers no conditions for choosing this over sibling tools such as carry_aftermath or carry_depth, and no when-not-to-use guidance.

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