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

Goes well beyond the readOnly/non-destructive annotations by disclosing the data source (live APY), the exact fee model (charged on principal, never yield; 0% direct vaults, 0.50% dropping to 0.25% above $1M), and the important edge case that net yield can go negative on short horizons with a net_is_negative flag. That is precisely the behavioral context an agent needs to interpret and explain results correctly.

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?

Front-loaded with the core purpose, then layers fee mechanics and return fields — each sentence carries information the agent needs given there is no output schema. It is a dense single paragraph that could be split into purpose/fee/return blocks for faster scanning, but nothing is redundant.

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?

Despite having no output schema, the description enumerates the returned fields (gross yield, platform fee, net yield, final balance) plus the net_is_negative flag, and explains the fee mechanics that determine those values. For a three-parameter read-only projection tool, nothing material is left unexplained.

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%, so the baseline is 3, but the description adds real meaning: it clarifies that target_id can address either a vault or a model portfolio and that omitting it projects across all products, and the $1M fee threshold gives amount_usdc consequence beyond its plain 'deposit amount' schema text.

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 and resource — projecting compound returns for a USDC deposit into an ACCRUE vault or model portfolio over a holding period — and distinguishes itself from siblings like compare_vaults or get_vault_details by being purely forward-looking. An agent can tell exactly what this computes 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 explicit trigger phrasing: 'Use this when the user asks "how much would I earn" or "what would my $X grow to"', which maps intent to tool cleanly. It stops short of naming alternatives or stating when not to use it (e.g. vs. compare_vaults for side-by-side rate comparison), so it falls one step below fully explicit routing.

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