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

Annotations cover the safety profile (not read-only, not idempotent, not destructive), and the description adds genuinely new behavioral facts: evaluation is asynchronous/on a schedule, firing is retrievable later, and it is premium-gated with an x402 pay-per-call or free-key path. It doesn't disclose limits on the number of standing alerts or what happens if an identical alert is re-registered.

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-loaded with the auth/pricing banner, then the core action, then type semantics, then the retrieval pointer. Nearly every clause carries information, though the bracketed premium banner and the trailing 'not investment advice' line consume space without helping invocation.

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 7-parameter mutation with an output schema present, the description covers auth, async evaluation, retrieval, and type semantics. Missing only edge-case behavior (alert limits, symbol validation against hl_get_markets, interaction with hl_delete_alert), which are minor given the rich 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 description coverage is 86%, so the schema already carries most semantics. The description still adds value by tying each type to its relevant parameter (funding_apr→aprThreshold as |annualized funding|, price_move→movePct/window, whale_net_flip→cohort), which the bare enum in the schema lacks.

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 ('Register a persistent alert the server evaluates on a schedule') and enumerates the three alert types with the exact condition each fires on. It also names hl_poll_alerts for retrieval, so an agent can distinguish it from the read-side siblings without opening any 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?

Explicitly routes the agent: call hl_request_free_key first if unauthenticated, and use hl_poll_alerts to retrieve fired events. It also gives the selection criteria among the three alert types. It stops short of stating when NOT to use it (e.g. one-off checks vs. standing watches) or any per-account alert caps.

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