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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. Beyond that the description usefully adds the exact formula and the default permittivity fallback, and it discloses a cost of 1 credit — a genuinely behavioral detail not present in annotations. It stops short of noting edge cases such as r = 0 or invalid negative distances.

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?

Two compact sentences with the core computation and formula front-loaded, followed by the medium/default note. The credit-cost parenthetical is short and earns its place, though it slightly interrupts the technical flow.

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 simple three-parameter calculator with no output schema, the definition covers inputs, formula and default medium adequately. The main remaining gap is that the output unit (V/m or N/C) and behavior at zero distance are not stated, which matters for interpreting results.

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?

Schema description coverage is 100%, so charge, distance and permittivity are already fully documented with units and the vacuum default. The description echoes the permittivity default rather than adding new meaning, so the baseline of 3 applies.

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 states a specific verb and resource ('Calculates the electric field strength produced by a point charge') and pins down the underlying formula (E = kQ/r²), so the agent knows exactly which physical computation this is. It is clearly distinguishable from adjacent calculator siblings such as potential_energy or wire_resistance.

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?

Usage is only implied: the agent can infer this is the tool for point-charge field calculations, but there is no explicit 'use this when…' statement, no note about when a different tool (e.g. potential_energy) is more appropriate, and no preconditions or exclusions.

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