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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description goes beyond them by disclosing the $0.002 call cost and warning that the result is not a building measurement and does not exempt a home from testing — genuinely useful behavioral context. It stops short of covering auth, rate limits, or response shape.

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 tight sentences, no filler: the first states what the tool returns and where, the second carries the cost and the key interpretation caveat. Front-loaded and fully earning its space.

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?

With no output schema, the description helpfully enumerates the returned data and discloses cost and interpretation limits, which is most of what an agent needs. The remaining gap is parameter handling — nothing explains how lat/lon and place interact or which is preferred.

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 only 33% (only 'place' has a description), and the description adds no guidance on lat/lon/place at all — not even the lat/lon accepted ranges or that place is a geocoded alternative. With low coverage the description should compensate, and it does not.

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?

Names a specific verb ('Look up') and resource ('area-level geologic radon potential'), then enumerates the returned fields (index, province, geology, EPA screening guidance) and the geographic scope (U.S. location). The sibling list is dominated by unrelated token/crypto endpoints, so no differentiation is needed for an agent to identify this tool.

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 ('look up ... for a U.S. location') and adds a cost signal plus an interpretive caveat that any home can have high radon and should be tested. However, it never states when to choose this over adjacent geospatial tools like find_superfund_sites or geocode_address, nor what prerequisites (e.g., place-string geocoding) exist.

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