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

With no annotations, the description carries the full burden, and it does disclose several useful behavioral facts: a default 90-day window, a fixed 200 km radius, a 25-postal-code cap, and PRO/subscriber gating (reinforced by the access_token parameter). It says nothing about how counts are grouped (per postal code vs. total), rate limits, or failure modes for unknown postal codes.

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?

A single tight sentence with no waste, and the substantive scope (counts, radius, postal codes) is front-loaded. The leading 'PRO.' token is cryptic but at least signals the paid tier immediately.

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 4-parameter tool with no annotations and no output schema, the definition is too thin: it never explains the shape of the result (per-postal-code breakdown vs. aggregate), leaves min_mag undocumented, and gives no guidance on token acquisition beyond what the schema field says. An agent could call it, but could not predict or interpret the response confidently.

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 coverage is only 25% (only access_token is documented), so the description must compensate: it does clarify the default for 'days' (90) and the maximum for 'postal_codes' (25), and it reveals that the 200 km radius is fixed rather than configurable. However, 'min_mag' is left entirely undefined in both schema and description, which is a real gap for a filter parameter.

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 names a concrete resource and operation — quake counts within a 200 km radius of postal codes — which is distinguishable from the sibling tools quake_search and recent_quakes (listing/searching events vs. aggregated counts). It never explicitly contrasts with those siblings, and the tool name 'sites_check' is actively misleading on its own, so the description is doing all the work.

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?

There is no statement of when to use this instead of quake_search or recent_quakes, and no exclusions or prerequisites beyond the cryptic 'PRO.' prefix. The agent must infer from the word 'counts' that this is an aggregation tool rather than an event listing.

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