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

Annotations already declare readOnly/idempotent/closed-world, so the safety profile is covered. The description adds genuinely useful behavior not in the annotations: the rule that zero depth is distinct from missing data, and the tier-gated expansion to ETH subscribers.

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?

Three compact sentences, each carrying distinct information, with the output content front-loaded. 'Under preregistered rules' is slightly opaque jargon but is the only mildly wasteful phrase.

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 no-argument, no-output-schema read tool, the description covers what is returned, the zero-vs-missing semantic, and tier scope. It omits how this differs from neighbouring tools, which is the main residual gap.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The schema is fully self-consistent (empty object, additionalProperties false).

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?

The description names the concrete data it returns: BTC depth-collapse onset, trough, and recovery, which is more specific than the title's 'Realized depth collapses'. It does not differentiate itself from siblings like unwind_watch or liquidity_tiers, so it stops short of a 5.

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?

There is no statement of when to reach for this tool versus the other liquidity/exit tools. The only usage-adjacent sentence ('Subscriber exit_desk_full adds ETH') describes scope entitlement, not a selection condition.

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