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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is fully covered. The description adds methodological context (each lens is measured against its 50-day average with a 20-day change; posture collapses to risk_on/risk_off/mixed) which is genuinely useful, but it does not address cost, latency, caching, or data staleness. With annotations carrying the safety burden, 3 is appropriate.

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?

Roughly two sentences, front-loaded with the resource and lens taxonomy before the output/posture detail and the optional parameter. Dense but every clause carries content; only the em-dash-heavy enumeration borders on list-dumping.

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 an output schema present the description need not explain return values, and rich annotations remove the need to restate safety. It covers purpose, interpretation of results (rising/falling, posture vocabulary) and the one parameter, leaving only sibling routing unaddressed for a read-only analytical tool.

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 single parameter is fully documented in the schema with an enum and its own description, so the schema already does the heavy lifting (coverage 100%). The description adds only that focus "adds lenses specific to that asset class" — a mild clarification of additive behavior, not new syntax or constraints. Baseline 3 fits.

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 — the intermarket environment read through named price-ratio lenses — and enumerates the exact lens families (asset-class rotation, risk appetite, defensive flows, dollar) plus the three possible postures. An agent can tell what this returns without opening the schema. It does not explicitly name a sibling it should be chosen over (e.g. get_macro_context or get_relative_strength), so it stops short of 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?

"A first-pass read of the market environment" implies the intended use as a top-level orientation call, and the focus parameter's effect is stated. However there is no explicit when-not guidance and no mention of the sibling tools (get_macro_context, get_market_breadth) that overlap this space, so the agent must infer routing.

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