open_file

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

Annotations declare readOnlyHint=false and destructiveHint=false, so the mutation/safety profile is partly covered. The description adds genuine value beyond that by explaining the side effect of launching the OS default handler for the file type. It omits focus-stealing behavior, blocking vs non-blocking execution, and failure modes for nonexistent paths.

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 core behavior is front-loaded in the first sentence and the rest is a short Args block. The Args block partially repeats the schema, but for a single-parameter tool this is minor waste rather than bloat.

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 one-parameter launcher with no output schema, the description covers what the tool does and what the argument should be. Remaining gaps (return value, error handling, whether it waits for the app) are modest given the tool's simplicity.

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 0%, so the description must carry the parameter, and it does: "path: Full path to the file or folder" conveys that an absolute path (not a name or relative reference) is expected. It adds the one distinction the bare schema lacks, though no format examples or quoting guidance.

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?

States a specific verb and resource ("Open a file or folder") and clarifies the mechanism ("in its default app"), including concrete examples of app routing (Finder for folders, Preview for PDFs). It does not, however, distinguish itself from close siblings like read_file or open_app, leaving the boundary to inference.

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 never says when to use this instead of read_file, open_app, or open_url, all of which are plausible alternatives in the sibling list. Usage is only weakly implied by "in its default app"; there are no exclusions or prerequisites.

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