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

The description discloses behavior beyond the annotations: 'local mode is read-only; Pro mode may call Axint endpoint when credentials are configured.' This nuances the readOnlyHint, clarifying that Pro mode may have external side effects. It also explains input weighting ('domain is only a weak hint; the app description wins'). No contradiction with annotations.

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 well-structured with 'Use:', 'Inputs:', 'Effects:' sections and front-loaded with the core function. It is somewhat verbose but each section has a purpose. The stray 'prompt/dir' input reference could have been omitted, but overall it remains readable and useful.

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 has 10 parameters and an output schema, the description covers the essentials: return format, mode behavior, and usage context. It does not need to explain return values due to the output schema. The minor parameter mismatch prevents a perfect score, but the description is largely complete for an agent to decide and invoke the tool.

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 100% description coverage, so the baseline is 3. The description does add useful context, e.g., appDescription takes precedence over domain. However, it mentions 'prompt is the product brief; dir adds project context', which are not actual parameters in the schema, potentially misleading the agent. This inconsistency prevents a higher score.

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 tool's purpose: 'Suggest Apple-native features for an app based on its description.' It uses a specific verb ('suggest') and resource ('Apple-native features'), and specifies the input basis ('app description'). It also distinguishes from siblings by noting it is 'not a substitute for registry search or validation.'

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?

Provides explicit usage guidance: 'Use: use before generation to choose Apple surfaces; not a substitute for registry search or validation.' This tells the agent when to use it and what it is not for. Also clarifies Pro mode is used only when configured, setting expectations.

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