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

Annotations already declare readOnly/idempotent and non-destructive, so the bar for extra credit is high. The description adds substantial beyond that: history window (252 trading days), pricing tiers (FREE+ vs PRO+), and exactly which intraday-derived columns appear for PRO+ subscribers. No contradictions with annotations.

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?

The description is front-loaded with the core purpose, then efficiently explains the date variants, access tiers, and PRO+ column additions. Each sentence carries meaningful information with no filler or repetition.

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?

Given the tool's moderate complexity (4 params, output schema present), the description covers all critical non-schema context: default behavior, date range semantics, time window, access-tier differences, and derived features. The presence of an output schema means return-format details need not be restated.

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 schema already describes all four parameters with full coverage, so the baseline is 3. The description goes further by clarifying the default when no date is supplied ('returns the most recent row') and how date/start_date/end_date collectively produce historical rows, adding value beyond the individual parameter docs.

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 opens with a specific verb+resource ('Get factor row for a ticker') and then explains the variant behaviors (most recent vs historical rows). It distinguishes the tool from siblings like get_market_context or get_labels by focusing on factor rows and the analogue-backtest use case.

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?

It gives clear context for when to use date arguments ('useful for honest analogue-backtests') and describes the default no-date behavior. However, it does not explicitly mention when to prefer an alternative sibling tool, so it stops short of a full 5.

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