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

Beyond the readOnlyHint and destructiveHint annotations, the description discloses detailed fee mechanics (charged on principal, never on yield, specific rates), the possibility of negative net yield over short horizons, and the presence of the net_is_negative flag. It also lists all returned values. This thoroughly explains the tool's behavior without contradicting annotations.

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 sentences, front-loaded with the primary purpose. It packs necessary detail (fee structure, return values, use case) without unnecessary fluff, though the fee explanation is dense and could be simplified. Overall it is well-structured and appropriately sized.

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?

Since there is no output schema, the description compensates by explicitly enumerating the return values (gross yield, platform fee, net yield, final balance) and the edge-case flag. It also covers the optional target_id behavior and mentions live APY data. For a calculation tool, this is sufficiently complete for an agent to set expectations.

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?

With 100% schema description coverage, the schema already explains all three parameters. The description adds meaningful context not in the schema: 'If omitted, projects across all vaults and portfolios' clarifies the target_id behavior, and the fee-on-principal explanation deepens understanding of the amount_usdc and months relationship to the result.

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 states the tool's function: 'Project compound returns for a USDC deposit into any ACCRUE vault or model portfolio over a given holding period.' This specific verb+resource combination distinguishes it from sibling tools like list_vaults or get_vault_details. The explicit use-case phrasing ('how much would I earn') further clarifies its purpose.

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 description provides clear usage context with the directive: 'Use this when the user asks "how much would I earn" or "what would my $X grow to".' This tells the agent when to invoke the tool, though it does not explicitly mention when not to use it or name alternative tools, which prevents a perfect score.

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