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

Goes well beyond the annotations: discloses cost ($0.075 per run, charged only when picks return), the free weekly cap vs. credit cap, and the ten-minute replay/caching window that explains the idempotentHint. It also gives the reader the reason readOnlyHint=false (credit side effect) without contradicting it.

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 dense sentences, front-loaded with purpose before pricing and caching details. Each sentence carries real information (scope, economics, idempotency). Slightly packed but no filler.

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 needn't be described. For a 9-parameter billing-aware tool, the description covers the essential purpose, cost model, and caching behavior, leaving only minor per-parameter detail gaps that the schema partially fills.

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 44% (below 50%), so the description should compensate, and it partially does by tying the 14-day window to from/to and the pick counts to max_picks/free. But it adds nothing for region, brief, category, or exclude_keys semantics. Partial compensation warrants a 3.

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+resource: 'Personal picks from the published Knossot calendar for a brief, in one region and a window of up to 14 days.' An agent immediately knows this returns curated event recommendations scoped by brief/region/date. Sibling differentiation (get_usage, list_regions) is only implicit, so it stops short of a 5.

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?

Provides meaningful context for *how* the tool behaves (free weekly run vs. credits, charge only when picks return), which indirectly tells the agent when to call it. However it never states when-not-to-use it or names an alternative among get_usage/list_regions, so usage routing is only implied.

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