physical_constants

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

No annotations are provided, so the description must carry the burden. It discloses basic behavior: a lookup or list operation, and mentions 22 constants. It doesn't address error handling, return format, or any side effects, but for a simple read-only lookup this is reasonably transparent.

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 well-formed sentence that packs all essential information without fluff. It front-loads the verb and provides examples inline, making it easy to scan.

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 straightforward lookup tool with one optional parameter and no output schema, the description sufficiently covers the essentials: what it does, how to use it, and what to expect (values for constants). Minor gaps remain (e.g., exact return format, error cases), but it's complete enough for a simple 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 input schema has one parameter 'name' with zero description coverage (0%). The description compensates by giving example values and explaining that omitting the name yields a list of all constants. This effectively communicates the parameter's meaning and the behavior for null.

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: look up a specific physical constant or list all constants. It provides concrete examples (speed_of_light, planck, etc.) and distinguishes two modes (specific lookup vs. list all). While it doesn't explicitly contrast with siblings like convert_units, the verb 'look up' is specific enough for the resource.

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 name for a single constant, omit it to list all. It doesn't explicitly state when to prefer this over convert_units or calc_exact, but the context is clear. Lacks explicit exclusions or guidance on when not to use it.

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