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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the useful scoping fact that results are market-wide rather than ticker-specific, but says nothing about coverage window, pagination, or freshness of the calendar data.

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 with the resource and scope front-loaded and no filler. It could arguably fold the 'when to use' clause into the first sentence, but there is no wasted text.

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?

An output schema exists, so return values need not be described, and annotations cover the read-only/open-world profile. The description supplies scope and intent, which is sufficient for a zero-parameter list tool; only the absence of sibling routing keeps it from a 5.

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?

The tool takes zero parameters, so there is nothing for the description to clarify and the baseline of 4 applies. The schema (additionalProperties: true) and description are consistent in implying a parameterless call.

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 (Lists) and resource (Google Finance earnings calendar entries) with a scope qualifier ('market-wide'), plus the payload shape ('company and instrument details when available'). It is distinguishable from the ticker-level google_finance_quote or yahoo_finance_ticker_earnings tools, though it never names a sibling explicitly.

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 for upcoming market-wide earnings context' gives a positive when-to-use cue, but offers no when-not guidance and names no alternative (e.g. yahoo_finance_calendars or ticker-level earnings tools), leaving the routing decision partly to inference.

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