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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds genuine behavioral context beyond that: values are read from the chain at past blocks, the series begins at vault deployment, and it computes window change and largest drawdown. It stops short of noting rate limits or pagination, so not a 5.

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 sentences, front-loaded with what the series contains before moving to provenance and comparison use. Dense but every clause carries information; no obvious padding.

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?

An output schema exists, so return-shape explanation is not strictly required, and annotations cover safety. The description supplies provenance, series start, and benchmark framing, leaving only minor gaps around pagination or point limits for a read-only tool.

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 coverage is 100% and both parameters (points, interval) are fully documented with defaults in the schema, so the baseline is 3. The description only vaguely gestures at the window via 'change of each over the window' and adds no syntax or default meaning beyond the schema.

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 specifies a concrete verb and resource: it returns the NAV per GBLIN share over time, enriched with the ETH/USD and BTC/USD oracle prices the vault uses plus change and drawdown. This is far more specific than a sibling like treasury.state could be, though it never explicitly names a sibling to distinguish itself from.

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?

Usage is implied rather than stated: the agent learns the history starts at vault deployment and can be benchmarked against holding ETH or BTC. There is no explicit when-to-use versus alternatives (e.g., treasury.state for current values) and no exclusions, so guidance is only implied.

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