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

Annotations already cover safety (readOnly/idempotent/non-destructive/non-open-world), and the description adds genuinely non-obvious behavior: every number carries its source and time, values failing a plausibility check are withheld rather than guessed, and polling is the intended retrieval model. The API-key requirement is also disclosed.

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?

Purpose and scope are front-loaded and most clauses carry real information. There is some filler (the dashboard attribution link, "Not financial advice", and the no-orders/no-funds sentence that partly restates annotations), which keeps it from being tight.

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 enumerates the returned fields, ordering, and the withholding rule, so an agent knows what it will receive. Parameters, prerequisites, and side-effect profile are all covered.

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%, so baseline is 3; the description goes further by explaining the cursor pattern ("Pass after_id = the last id you saw to get only new ones"), which tells the agent how to use the parameter rather than just what it filters. The limit parameter is left entirely to the schema.

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 alerts that fired for your agent") with ordering ("oldest first") and the exact payload fields (what crossed, value, price, Animal Spirits reading, coin page). The "for your agent" scope plus the incremental-cursor framing cleanly separates it from the sibling crypto_alerts_list / crypto_alert_create / crypto_alert_kinds.

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?

"Poll this when you have no webhook" gives an explicit trigger condition, and "Needs a registered agent (API key)" states a prerequisite. It does not, however, name or contrast with the sibling listing tool (crypto_alerts_list), so the alternative-selection guidance is only partial.

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