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

Annotations already declare readOnly/idempotent/openWorld, so the safety profile is covered; the description adds genuinely new context by disclosing which sections are Pro-gated (levels, crowding) and that some sections appear conditionally (standout 'if any', record 'present on a quiet coin too'). It does not mention latency, rate limits, or what happens when a coin is unknown.

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 is front-loaded in the first clause, which is good. But the middle is a dense, comma-spliced inventory of every output section that overlaps heavily with the output schema, making the paragraph longer than needed for an agent to select and call it.

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 6-parameter aggregation tool with an output schema, the description covers the meaningful gaps: view mode semantics, Pro gating, and conditional sections. It is complete enough to call correctly, with only minor omissions around the non-default output-shape parameters.

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 the baseline is 3. The description does carry the real meaning of the view enum (schema only says 'Which lane; see the description'), which is added value, but cursor, detail, compact and position_usd are untouched in the description and only minimally covered by 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 and scope ('the one-call answer for ONE coin') and enumerates the content in causal order, which makes its bundling role unmistakable. It never names a sibling tool (market_now, coin_search, what_followed) to draw the boundary, so differentiation is inferred rather than stated.

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 framing 'answers "why is X moving" without a second call' gives a clear use case, and the view lanes imply when to pick quick/funding/crowding. However, there is no explicit when-not guidance and no routing away from siblings like coin_search (to resolve a symbol) or market_now (for market-wide context).

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