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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower, and the description clears it by disclosing tiered access behavior: 3 trades without an account, 5 with a free key, full feed for Pro, plus the fields each tier returns. It does not cover rate limits or refresh cadence, but the tier disclosure is genuinely useful context beyond the 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?

Two dense sentences: the first defines the signal and payload, the second gives example queries and tier limits. Every clause earns its place and the access tiers are grouped compactly at the end.

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 single-optional-parameter, no-output-schema tool, the description supplies the qualifier definition, example intents, returned fields, and tier-dependent result sizes, which is nearly everything an agent needs. It stops short of describing response shape or sort order, which matters given there is no output schema.

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 'limit' parameter, so the schema already documents default and bounds. The description never references limit directly, but the tier caps (3/5/full) and the field list tacitly frame what comes back; this adds contextual value without adding parameter-level syntax, so baseline 3 is right.

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 (unusual options activity this session) and defines the qualifying signal precisely: large, sweep-like, or volume-versus-open-interest outlier orders. The subject matter is clearly distinct from siblings like darkpool_ranking or insider_trades, though no sibling is named explicitly, which keeps it just short of a 5.

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 concrete example phrasings ('any unusual options activity in NVDA?', 'biggest options trades today') that map a user intent directly onto this tool. No explicit when-not-to-use guidance or named alternatives, so it stops at clear context rather than full routing.

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