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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuinely new context: the data source (CoinDesk Data / formerly CryptoCompare), cross-exchange aggregation, and that a user-supplied API key is mandatory — none of which annotations convey.

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 compact sentences, front-loaded with the core action, with the key requirement (own API key) stated last as a gate. No filler, though the parenthetical rename and 'aggregated across major exchanges' slightly compress several ideas into one clause.

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 need not be explained, and annotations cover safety. However, for a 6-parameter tool with 17% schema coverage, the description leaves the exchange-filter and sign parameters entirely opaque, which is a real gap for correct invocation.

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 only 17% across 6 parameters, so the description must compensate. It does clarify the two most important ones semantically (fsym = one coin, tsyms = many fiat/crypto symbols), but e (exchange filter), sign and extraParams are left undocumented in both description and 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 verb and resource ('Current crypto spot price'), plus the scope: one fsym quoted in many tsyms, aggregated across major exchanges. An agent can distinguish it from historical siblings like histo_day/histo_hour, though no sibling is named explicitly in the description.

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?

The word 'Current' implies when to use it (live spot lookup rather than history), but there is no explicit when-not guidance or named alternative in the description body. The useful fallback advice ('without a key, use the `crypto` pack') lives only in the _apiKey schema description, not the tool description.

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