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

No annotations exist, so the description carries the full burden. It discloses the exact operation and result ('returns a & b'), making the behavior transparent for a pure function. It does not cover edge cases like integer bounds or coercion, but for a simple bitwise operation this is adequate.

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 brief and front-loaded, with two useful sentences. The 'Bit And:' prefix is slightly redundant with the tool name, but it does not detract significantly from the overall succinctness.

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?

For a simple two-integer bitwise operation with no output schema or annotations, the description is complete: it specifies inputs, the operation, and the return value. An agent has everything needed to call it correctly.

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 input schema defines zero parameters, yet the description names the two arguments ('a and b') and states they are integers. This adds essential meaning that the schema completely lacks, fully compensating for the empty parameter definition.

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 uses a specific verb and resource: 'Perform a bitwise AND operation between two integers.' It clearly identifies the operation as AND, distinguishing it from sibling tools like x402-bit-or and x402-bit-xor without requiring schema inspection.

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 context is clear: use this tool when a bitwise AND on two integers is needed, and the return expression 'returns a & b' confirms the expected behavior. However, it does not explicitly mention alternatives such as bit-or or bit-xor, or state when not to use this tool.

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