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

Annotations already declare readOnly/idempotent/destructive-free and closed-world, so the safety profile is covered. The description adds genuinely new behavior: Free tier yields only match counts and jurisdictions, while Pro yields named entities with contact channels — that materially affects how results should be interpreted. No pagination or rate-limit detail, hence not a 5.

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?

Three sentences, no filler: trigger context first, capability second, tier-dependent output third. Every sentence carries information an agent needs.

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 an output schema present, return values need no explanation, and the description covers use-case, inputs, and tier behavior. The one gap is that zero parameters are required, yet the description never says what a call with neither query nor country returns.

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 100% and both parameters are self-documenting with their own examples. The description's country examples and "by country or free-text query" framing largely restate the schema, so baseline 3 applies; it adds no syntax, format, or combination guidance.

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?

States a specific verb (screens) and resource (MiningBridge counterparty directory) with concrete scope: miners, refiners, processors, recyclers, traders of critical minerals, by country or free-text. The entity set and data source make it plainly distinguishable from siblings like search_trade_flows or get_commodity_snapshot.

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?

"Use this when the user is looking for miners, refiners..." gives a clear triggering context with examples of jurisdictions. There are no explicit exclusions or named alternatives, so it stops short of a 5, but an agent knows when to reach for it.

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