market_snapshot

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

With no annotations, the description carries the full burden, and it does disclose the as-of fallback behavior (latest row on or before the date, implicitly covering non-trading days) and the exact payload contents. It says nothing about invalid-ticker behavior, date-format/timezone expectations, data freshness/latency, or rate limits, which matters for a data-fetch tool with zero annotation coverage.

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 sentences, front-loaded with the resource and its scope, followed by the trust directive. The indicator parenthetical is dense but functional; no filler wording. Slightly compressed enough that the look_back_days role is buried.

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 snapshot tool with an output schema covering return values, the description supplies what the schema cannot: as-of fallback semantics, payload contents, and a trust/authority directive. Remaining gaps (date format, look_back_days range, error behavior) are modest given the output schema exists.

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 0%, so the description must compensate. It meaningfully defines as_of ('on or before') and hints that look_back_days governs 'recent closes', but never explains the look_back_days window explicitly, nor ticker format or accepted date formats — leaving real gaps across 3 undocumented parameters.

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 resource and content: 'the latest OHLCV row on or before as_of' plus named indicators (moving averages, RSI, MACD, Bollinger, ATR) and recent closes. This implicitly separates it from price_history (range series) and technical_indicators (indicator-only), but no sibling is named explicitly, so an agent must infer the boundary.

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?

'Treat it as the source of truth for any exact price or indicator figure you state' gives a concrete usage directive that tells the agent when to reach for this tool over estimating or recalling numbers. It stops short of naming alternatives or stating exclusions, so the routing vs price_history/technical_indicators is left implicit.

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