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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral context beyond the schema: the $0.002 cost per call, UTC timezone, and that data comes from official calendars (BLS, BEA, ECB). Return format/pagination is not described, keeping it out of 5 territory.

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, front-loaded with what the tool returns and back-loaded with the call-to-action. No filler, though the parenthetical cost and long event list make it slightly dense.

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 read-only, zero-required-parameter calendar lookup with no output schema, the description covers source, timezone, cost, event scope, and the intended moment of use. Nothing an agent needs to call it correctly is missing.

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% with enums for region and importance, so the schema already documents all three parameters thoroughly. The description adds only light reinforcement ('in UTC with importance') and no syntax or format detail beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 specific resource (upcoming market-moving events) and enumerates the concrete event types covered (CPI, jobs report, PCE, GDP, PPI, JOLTS, FOMC, ECB), plus the authoritative sources (BLS, BEA). It is clear what the tool returns, though it does not explicitly contrast itself with siblings like market.explain_move or news.symbol.

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?

'Check before opening a position' gives a clear, actionable usage context tied to pre-trade workflows. It stops short of naming alternatives or stating when NOT to use it, so it falls one notch below the explicit when/alternative guidance of a 5.

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