validate_isbn

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

The description explains the verification actions (checking prefix and check digit) and what happens on failure (returns expected check digit). However, it does not specify the return value on success or error handling. Given no annotations, the description adds moderate behavioral context but misses some 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 two concise sentences, front-loaded with the primary action, and contains no redundant words. Every sentence serves a purpose.

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 description covers the tool's core behavior, failure output, and compares to 'trusting digits.' For a simple validation tool with one parameter and no output schema, it is nearly complete. Minor gap: does not state success return type, but this is inferable.

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% with a parameter description that allows hyphens/spaces. The tool description reinforces that and adds context about validation logic, but does not significantly augment parameter meaning beyond the schema. Baseline of 3 is appropriate.

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 verifies an ISBN-13 identifier, distinguishing it from the sibling tool 'validate_isbn10' by specifying ISBN-13. It mentions specific checks (prefix and check digit), making the purpose explicit and unique.

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 indicates when to use the tool ('USE THIS to verify...') and implies it should be used instead of trusting raw digit strings. While it does not explicitly mention the sibling 'validate_isbn10' for ISBN-10, the context from sibling tools provides clear differentiation. The guidance is adequate but lacks explicit exclusions.

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