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

No annotations are provided, so the description carries the full burden. It discloses the read-only nature (snapshot taken straight from the venue's public API), the freshness behavior (stamped with moment it was read), and the market cap (25). It does not address edge behavior like rate limits or error handling, and it stops short of explicitly saying 'read-only', but for a benign read tool the disclosure is solidly above minimal.

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 sentences, zero waste. The scope and field list are front-loaded, and the usage routing is appended as a clean tail. Every clause earns its place.

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?

An output schema exists, so return values are covered elsewhere. The description complements it by naming the data source, the freshness stamping, the field set, and the market limit. For a single-parameter snapshot tool, nothing an agent needs to call it correctly is missing.

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 'coins' parameter, so the baseline is 3. The description reinforces the 1..25 bound ('for up to 25 markets') that the schema also states, but adds no distinct semantic beyond what the schema already documents.

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 action ('What is happening right now') with a concrete resource (live market snapshot) and enumerates exact fields returned (mark price, hourly funding, open interest, 24-hour notional, premium). The 'up to 25 markets' scope and the explicit contrast with daily tools distinguish it from 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?

Gives explicit selection guidance: 'Use this for "now" questions; the daily tools answer completed days only.' This states both when to use and when not to, pointing to the alternative category. No inference is required of the agent.

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