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

With no annotations, the description carries the full burden and does reasonably well: it discloses data provenance ('reconstructed from actual on-chain swaps') and scopes the metric to the vault's own purchases rather than live market data. It doesn't explicitly state read-only status or confirm no side effects, but for a zero-parameter read tool the provenance disclosure adds genuine value.

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 the core purpose and the returned metrics before the clarifying comparison. The parenthetical asset examples are compact, and nothing is wasted.

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?

With no output schema, the description must convey return values, and it does list them (cost basis, average cost, current value, return, in USD and SOL). For a simple no-param read tool this is nearly complete, with only minor gaps around format or empty-data behavior.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. No parameter-level detail is needed or missing.

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 verb+resource ('vault's REAL position performance per RWA') and enumerates what it returns: cost basis, average cost, current value and return in USD and SOL. It explicitly distinguishes itself from market price history, letting an agent separate it from siblings like get_rwa and list_rwas.

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?

The closing clause 'Distinct from an asset's market price history: this is how the vault's own buys have done' gives clear context for when this tool is the right choice. However, it doesn't name a specific alternative tool to route to, and gives no exclusions or prerequisites beyond that positioning.

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