acos

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

No annotations are provided, so the description carries the full burden. It mentions 'domain validation,' which implies input constraints (likely -1 ≤ value ≤ 1), but does not detail error handling, output format (radians vs. degrees), or performance characteristics. For a mathematical function with no annotations, this is a significant gap in behavioral disclosure.

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 highly concise and front-loaded: it states the core function in the first phrase and adds domain/category context efficiently. Every sentence earns its place with no wasted words, making it easy for an agent to parse quickly.

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 complexity (mathematical function with domain validation), no annotations, no output schema, and low schema coverage, the description is incomplete. It lacks details on output (e.g., radians), error cases, and sibling differentiation, making it inadequate for reliable tool invocation without additional inference.

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 input schema has 1 parameter with 0% description coverage. The description adds some context by implying domain validation for the 'value' parameter, but does not specify the exact domain or units. Since schema coverage is low, the description partially compensates but not fully, aligning with the baseline for minimal param info.

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: 'Calculate arccosine (inverse cosine) with domain validation.' It specifies the mathematical operation (arccosine) and mentions domain validation, which is a key aspect. However, it does not explicitly differentiate from siblings like 'acos_degrees' or 'asin', though the domain/category hints at trigonometry.

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 minimal usage guidance. It mentions 'domain validation' but does not specify when to use this tool versus alternatives (e.g., 'acos_degrees' for degrees output, 'asin' for arcsine). No explicit when/when-not instructions or prerequisites are given, leaving the agent to infer from context.

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