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

With no annotations, the description carries the full burden of behavioral disclosure. It does disclose important operational requirements: a ChainHelix API key as bearer token, or a per-call payment of 2 cents via specific methods. It also defines the session boundaries precisely. However, it omits other behavioral traits such as response format, data recency, or potential errors, leaving the agent uncertain about execution behavior.

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 compact and front-loaded with critical operational information. The first sentence packs auth/payment details efficiently, and the next two sentences define the metric and session times. It is somewhat dense but every sentence adds information, and there is no redundant fluff.

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?

Given the simple one-parameter schema and the presence of an output schema, the description adequately explains the core purpose and session definition. However, it does not explain the role of the 'chain' parameter, nor does it clarify whether the output is per-chain or aggregate. The heavy focus on payment rather than functional context leaves some gaps in understanding what the tool actually does.

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 schema has one optional 'chain' parameter with an enum, but the description never mentions it. With 0% schema description coverage, the description should at least explain what 'chain' affects (e.g., which asset's session stats are computed), but it remains silent. The enum provides some hint, but the agent has to guess whether the parameter is required, what default exists, and how it relates to the described metric.

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 clearly identifies the tool's output: 'Share of price movement per trading session over 7 days.' It specifies the sessions (Asia, London, New York in UTC thirds) and the time window (7 days), providing a specific resource and scope. However, it lacks an explicit verb like 'retrieve' or 'return,' and does not differentiate from sibling tools such as market_state or iv_summary, 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?

No guidance is provided on when to use this tool versus alternatives. The description focuses almost entirely on authentication and payment requirements, with no mention of use cases, prerequisites, or exclusions. The extensive sibling list further highlights the absence of any comparative direction.

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