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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the bar is lower; the description earns credit for disclosing the premium auth flow (free key vs x402 payment) — a real invocation blocker not in the schema. It also flags that venue spreads are conditional on predictedFundings being available, which is genuine behavioral context.

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?

One dense paragraph that front-loads the premium/API-key caveat before the functional description, which is the right ordering for an agent. It is slightly packed — the pricing and disclaimer clauses compete with the core purpose sentence — but nothing is redundant.

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?

Output schema exists, so return values needn't be spelled out, and the description still sketches what comes back (ranked markets, sign, spreads). Auth, filtering, and the conditional-spreads caveat are covered; pagination behavior via limit/offset is the only silently assumed piece.

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?

With 50% schema coverage the description must compensate, and it does: it explains side semantics (longs-pay vs shorts-pay), the min |APR| and OI/volume filters, and what includeVenueSpreads controls. Only limit/offset go unaddressed, and those are conventional pagination defaults.

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 — 'Screen every Hyperliquid perp by annualized funding' — and enumerates the three analytical outputs (top |funding|, sign, cross-venue spreads). It is clearly distinguishable from siblings like hl_get_funding_history (history for a market) and hl_vault_screener (different resource).

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 use cases — carry candidates and delta-neutral strategies — plus the prerequisite that a key is needed (call hl_request_free_key or pay via x402). It does not name a specific alternative to use instead for, e.g., per-market funding history, so it falls short of explicit when-not guidance.

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