copy_file

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

The description states 'Fails if destination exists', which means a second identical invocation would fail because the destination now exists. This contradicts the annotations' idempotentHint: true, so the description directly conflicts with structured metadata.

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 concise and front-loaded with the core operation and a critical failure condition. The parameter list is slightly redundant with the schema but remains scannable and does not introduce unnecessary verbosity.

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?

Despite having an output schema and annotations, the description lacks usage guidance versus sibling tools and does not resolve the idempotence contradiction. It also omits practical details like path semantics, which are important for safe invocation of a file 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?

The schema has 0% description coverage, so the description must compensate for parameter meaning. It lists source and destination as required and adds the destination-existence failure condition. However, it does not explain path formats, whether the source must exist, or destination directory handling, so compensation is incomplete.

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 ('Copy') and resource ('a file'), clearly conveying the operation. It also adds the key constraint that it fails if the destination exists, which helps distinguish it from move_file and write_file.

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 no guidance on when to use copy_file versus sibling tools like move_file or write_file. It does not mention alternatives, exclusions, or prerequisites, leaving the selection rationale entirely to the agent.

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