pi

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 states the tool 'Get[s]' π, implying a read-only operation that returns a constant value. However, it does not disclose behavioral traits such as whether this is a static retrieval, if there are any rate limits, or what the return format is (e.g., a float, string, or object). The description adds basic context but lacks details on behavior beyond the core purpose.

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 immediately states the purpose, provides the value and definition, and adds domain/category context in parentheses. Every sentence earns its place with no waste, making it easy for an agent to quickly understand the tool's function.

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's simplicity (0 parameters, no annotations, no output schema), the description is adequate but could be more complete. It explains what the tool does but does not specify the return type or format (e.g., float precision, string representation). For a constant-retrieval tool, this is a minor gap, but the description is mostly sufficient for basic use.

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 0 parameters with 100% coverage (empty object), so no parameter documentation is needed. The description does not discuss parameters, which is appropriate. Baseline is 4 for 0 parameters, as the schema fully covers the absence of inputs, and the description correctly focuses on the tool's purpose without redundant parameter 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: 'Get the mathematical constant π (pi) ≈ 3.14159. The ratio of a circle's circumference to its diameter.' It specifies the exact resource (the mathematical constant π) and provides its approximate value and mathematical definition. This distinguishes it from sibling tools like compute_pi_chudnovsky or compute_pi_leibniz, which are algorithms for computing π, whereas this tool simply retrieves the constant value.

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 clear context with 'Domain: arithmetic, Category: general,' indicating this is a general-purpose arithmetic constant. However, it does not explicitly state when to use this tool versus alternatives like compute_pi_chudnovsky (which computes π via an algorithm) or pi_digits (which might return more digits). The guidance is implied but not explicit about alternatives.

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