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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds genuinely new behavior: the 'one market day delayed' data freshness, the null-with-note outcome when a name is on neither list, and the error path where unknown symbols return the valid-symbol directory. These are real traits beyond the structured fields.

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?

Front-loads the resource ('One stock's Coil read, headline fields') before the field enumeration, and the free-sample constraint is placed last. It is dense with long parentheticals, but each clause (value sets for entry window, null case, delay) carries information rather than filler.

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?

With no output schema, the description carries the return-field burden and does so field-by-field, plus edge cases (unknown symbol, no-list null). Combined with annotations covering safety and idempotency, an agent has enough to call it correctly; only the missing sibling routing keeps it short of full marks.

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 coverage is 100% for the single symbol param, so baseline would be 3, but the description adds meaning the schema lacks: the valid coverage universe, 'one symbol per call', and the behavior on an unrecognized symbol. That materially sharpens what a valid input is.

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+resource ('One stock's Coil read') and then enumerates the exact fields returned (board-percentile band, entry window, hold label, leadership flag, price move, earnings days, regime). It also implies the sibling split from get_stock_read_live by noting the free sample is 'one market day delayed', though it never names that sibling directly.

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?

No when-to-use or when-not-to-use guidance. The coverage note ('Covers any S&P 500, Nasdaq-100 or macro name') is scope, not routing guidance, and no alternative (e.g. get_stock_read_live, get_full_board, get_day_board) is named or contrasted. The agent must infer the choice purely from the delay clause.

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