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

With no annotations, the description carries the full behavioral burden and does so thoroughly: small-n warnings, the evidence block's gate_applies_to, study_finding NULL semantics, vs_unconditional_drift separating raw drift from excess, circular-horizon suppression, min/max withheld below n=8, and the [API Pro tier] requirement. This is well beyond what any structured field declares.

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 core purpose is front-loaded in the first clause, but the body is a dense ~450-word block with heavy parenthetical stacking that is hard to scan. Most sentences do carry non-redundant information, but the volume and nesting hurt readability and some preset/parameter detail duplicates the schema.

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?

There is no output schema, so the description must carry the return shape and it does: preset_definition, current_state_matches, last_matching_date, study_finding, vs_unconditional_drift, evidence, and path_statistics with its own suppression rule. Nothing an agent needs to interpret the response is missing.

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 100%, so the schema already documents all seven parameters, including the fixed-step enum for vol_rank_threshold and the circularity rule for condition_on_direction. The description largely restates these rather than adding syntax or format detail the schema lacks, so the baseline 3 applies.

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 output: a conditional forward-return distribution for a named preset cycle state, over matched historical episodes. It also distinguishes itself from siblings by explicitly naming arena_get_volatility_history, arena_get_cycle, and arena_dip_scenario and stating the relationship to each. An agent can tell exactly what this returns without opening the schema.

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?

Gives rich conditional context: which presets apply per asset, what include_path adds, when study_finding_applies is false, and names three related tools with their differing roles (the series behind the preset, the current state, the tranche composer). It lacks an explicit 'use this instead of X when Y' exclusion, but the routing context is strong.

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