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

Annotations already declare readOnlyHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavior the annotations cannot convey: a 30-day retention window, sampling that starts on first request, and the absence of historical backfill — all of which affect whether a call will return useful 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 no waste. The availability constraint is stated up front, and the no-backfill caveat is placed last where it reads as a clear warning.

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 is present, so return values need not be described, and the annotations cover safety. The description adequately covers availability limits. The only gap is scope — it never says what market or universe these snapshots cover — but for a zero-parameter tool this is a minor omission.

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, which is the baseline-4 case. There is nothing for the description to clarify beyond what the empty schema already communicates.

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 precisely identifies the resource: persisted hourly market-sentiment and regime snapshots. It implicitly distinguishes itself from the get_market_sentiment and get_market_regime siblings by framing this as the historical/persisted version, though it never states a retrieval verb or names the siblings 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?

The sampling and no-backfill caveats tell the agent when data actually exists, which is a meaningful usage condition. However, there is no explicit guidance on when to call this versus get_market_sentiment or get_market_regime, so the routing decision is left to inference.

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