open_file

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

With no annotations provided, the description carries full burden. It discloses the implementation detail ('macOS open command') which is valuable behavioral context, but doesn't mention potential side effects like launching applications, system permissions needed, or error conditions. It adequately describes the core behavior but lacks comprehensive operational 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 a single, efficient sentence that front-loads the core purpose and includes implementation detail without unnecessary elaboration. Every word serves a purpose, making it appropriately sized and well-structured.

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 moderate complexity (2 parameters, no output schema, no annotations), the description provides sufficient context for basic usage. It explains what the tool does and how it's implemented, though it could benefit from mentioning typical use cases or limitations. The absence of output schema means return values aren't documented, but this is acceptable for this type of system operation.

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 100%, so the schema already fully documents both parameters. The description doesn't add any parameter-specific information beyond what's in the schema, such as path format examples or application compatibility details. This meets the baseline for high schema 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 clearly states the specific action ('Open') and resource ('a file or directory') using the system default application, with explicit mention of the macOS 'open' command implementation. It distinguishes from the sibling 'reveal_in_finder' by focusing on opening rather than revealing.

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 implies usage for opening files/directories with default applications, but provides no explicit guidance on when to use this tool versus alternatives like 'reveal_in_finder' or when not to use it. The context is clear but lacks comparative or exclusionary statements.

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