open_app

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

Annotations give readOnlyHint=false and destructiveHint=false, so safety is partly covered; the description adds genuinely useful behavior beyond that by disclosing the idempotent 'bring to front if already running' semantics rather than assuming a fresh launch. It does not mention what happens if the app name is not found or any permission prompts, which keeps it short of a 5.

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?

One front-loaded sentence states the core behavior and the edge-case behavior, followed by a compact arg line with examples. Every element earns its place and nothing is padded.

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 single-parameter tool with annotations covering the safety profile and no output schema, the description supplies name format, examples, and the already-running case. The only real gap is failure behavior for an unknown app name, which is minor.

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 0%, so the description carries the burden, and it does so by specifying the expected string form ('as it appears in /Applications') plus three concrete examples. That is meaningful format guidance beyond the bare string type, though it omits any note on case sensitivity or whether extensions are required.

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 (open) plus resource (app), and adds the precise scope distinction that the app is brought to the front if already running. This clearly separates it from siblings like open_file, open_url, and list_apps without needing to name them.

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?

Usage is implied by the verb and the /Applications naming convention, but there is no explicit guidance on when to pick this over open_file, open_url, or list_apps (to discover valid names), nor any stated prerequisite such as automation permission. Implied-but-not-stated places it at the minimum viable level.

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