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

The annotations already mark this as read-only and idempotent, and the description adds useful behavioral scope: it is limited to BTC by default, is two-sided (bid/ask), and varies by subscription level (exit_desk_full adds ETH and a venue-failure scenario). It does not describe response format or interpretation, but for a read-only, zero-parameter metric tool this is acceptable contextual disclosure.

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 short sentences front-load the core product (BTC two-sided depth concentration) and its key metrics before adding the subscriber conditional. Every clause adds information and there is no filler, repetition, or unnecessary qualification.

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 zero-parameter read-only tool with no output schema, the description provides enough to invoke it: the asset (BTC), the side (two-sided), the metrics returned, and a subscription condition that changes scope. It does not define terms like 'effective venue count' or specify whether output is returned as a single snapshot, but these are secondary for a simple data retrieval call.

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 input schema is an empty object with 100% schema description coverage, so there are no parameters to document; the baseline for zero parameters is 4. The description contributes no parameter details because none are needed, and it does not introduce any undocumented inputs.

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 identifies the resource ('BTC two-sided depth concentration') and enumerates returned metrics (HHI, effective venue count, top venue, per-venue depth), so an agent can tell what the tool reports. It lacks an explicit verb such as 'returns' or 'calculates,' and it does not explicitly distinguish itself from siblings like liquidity_tiers or depth_episodes, so it falls 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 about when to use this tool instead of liquidity_tiers, depth_episodes, or crypto_exit_check. The subscriber note ('adds ETH and the venue-failure scenario') describes access-tier scope, not a decision rule for choosing between tools, so the agent is left without routing guidance. This is effectively no usage guidance beyond what the title implies.

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