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

Annotations already declare this a safe, idempotent, closed-world read, yet the description adds substantial context beyond them: it is an end-of-day stamped snapshot rather than a live tick, snapshot_ts must be read and stated, iv_pct/atm_iv_pct are percent while atm_iv_change is percentage points, nulls mean unavailable (iv_unsolved, illiquid, pcr_undefined) and must render as '—', and it must not recommend a strike or strategy. This is unusually rich behavioral disclosure.

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?

Dense but front-loaded: purpose, then usage triggers and sibling routing, then snapshot/unit/null caveats, then presentation constraints. Each block carries distinct operational value and no sentence merely restates the name or annotations.

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 full burden of describing returns and it does so: field names (snapshot_ts, iv_status, atm_offset, available_expiries), unit conventions, and null-vs-zero semantics are all covered. An agent has everything needed to call it and report results correctly.

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 100%, so expiry, symbol/ticker/identifier aliases and strikes-per-side are already fully documented in the schema; the description adds no input-parameter syntax or constraints. Baseline 3 applies, with the description's detail concentrated on output fields instead.

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 and resource ('Get the INDEX OPTION CHAIN') and enumerates the payload of interest (IV, Greeks, bid/ask, OI by strike). It explicitly differentiates itself from get_option_iv_history and from stock-option coverage, so an agent can place it among siblings without opening a schema.

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?

Gives explicit triggering questions ('show me the NIFTY option chain', 'what is the ATM IV', 'where is max pain', 'put-call ratio') and names the alternative (get_option_iv_history) with its broader underlying coverage. It also states the negative case (stock options are not collected) and how to phrase it, which is exactly the routing detail an agent needs.

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