physical_constants

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

No annotations are provided, so the description carries the full transparency burden. It discloses a safe read operation and the list-all behavior with values, but it does not mention invalid-name handling or case sensitivity. For a simple lookup, this is reasonable.

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 a single sentence with a front-loaded verb and concrete examples, containing no wasted words. It efficiently covers both lookup and list modes.

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, read-only lookup tool, the description covers input modes, example values, and output count. The presence of an output schema means return-value details need not be in the description, making it complete.

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 defines only an optional nullable 'name' with no descriptions, so the description compensates well. It provides example constant names and implies that omitting 'name' returns all 22 with values, effectively documenting the parameter's behavior.

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 uses a specific verb 'Look up' with a clear resource ('physical constant'), lists concrete examples, and explicitly states the list-all-22 alternative. This clearly distinguishes it from sibling calculation and conversion tools.

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 implies usage—provide a constant name to look it up, or omit it to list all—but it gives no explicit when-to-use/when-not-to-use guidance or alternatives. With many sibling tools, this is adequate but not illuminating.

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