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

Annotations already declare the tool read-only and idempotent, so the safety profile is covered. The description adds non-obvious meaning beyond that: 'Zero episodes is distinct from missing observations' clarifies a potentially misleading data-absence case, and 'Subscriber exit_desk_full adds ETH' discloses subscription-dependent output. It does not describe exact output fields or time bounds, but for a zero-parameter read-only tool this is meaningful 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?

The description is three short sentences, each carrying distinct information: the core output, the zero-vs-missing data interpretation, and the subscriber-dependent ETH coverage. It is front-loaded with the main subject and contains no filler.

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, idempotent tool with no output schema, the description covers the main return concept (collapse episodes with phases), the critical zero-vs-missing distinction, and the ETH variant. It is slightly underspecified about what 'pre-registered rules' precisely are and the exact output shape, but the tool's simplicity makes the description largely sufficient.

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 has zero properties, so there are no parameter semantics to document. With 0 params, the baseline is 4, and the description's scope statement is sufficient; no parameter-level elaboration is needed or possible.

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 a concrete resource: 'Realized BTC depth-collapse episodes, onset, trough and recovery under pre-registered rules.' This is specific enough for an agent to know what data is being exposed. It lacks an explicit verb like 'lists' or 'returns,' and it does not actively differentiate from sibling tools by name, which keeps it below the top score.

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 explicit when-to-use guidance or alternative tool comparison, but the description implies this is for querying realized depth-collapse episodes and offers a relevant eligibility condition: 'Subscriber exit_desk_full adds ETH.' This helps an agent understand scope and output variation, though it does not say what to use instead for related liquidity, exit, or venue metrics.

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