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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the description does not need to repeat safety traits. It adds value by disclosing that the tool 'Outputs structured arbitrage opportunities with rate differentials and confidence scores,' which is behavioral information beyond the annotations. No contradiction.

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 three sentences, front-loaded with the core function, followed by the target user and key inputs/outputs. Every sentence earns its place without redundancy or waste.

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?

The tool has 5 optional parameters and an output schema, so the description adequately covers purpose, target, inputs, and output type. It does not mention potential limitations or explicit exclusions, but given the annotations and output schema, it is reasonably complete. Minor gaps like not describing minDifferential or async behavior (though async is covered in the schema) prevent a 5.

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% (only 'async' has a description). The description mentions 'optional date ranges and currency filters,' covering startDate, endDate, and currency at a high level, but it completely omits 'minDifferential,' which is a key parameter for arbitrage scanning. With such low schema coverage, the description should compensate more fully, but it does not.

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 the verb 'Scans for arbitrage opportunities' and specifies the exact market pair (repo rates via ECB vs. short-term funding via Treasury Direct), which distinguishes it from other arbitrage tools. The target audience (CFOs) and output nature further clarify its unique function.

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 clear context by stating the tool is 'Designed for CFOs to identify cost-effective funding strategies,' indicating the intended use case. However, it does not explicitly state when not to use it or compare with alternative arbitrage tools, so it falls short of a 5.

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