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

With no annotations supplied, the description carries the full burden and does real work: it discloses return field semantics, explains how summary.cumulativeEarnedUsd reconciles to Morpho pnl, and warns that a deposit missing from the ledger counts as principal rather than earnings. What it omits is operational behavior — auth requirements, empty-state results, or freshness of the data.

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?

Four sentences, front-loaded with the resource and its returned fields before the accounting caveats. Each sentence carries information, though the ledger/pnl reconciliation sentences are dense and assume familiarity with Morpho terminology.

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?

There is no output schema, so the description must describe returns, and it does name the key per-vault fields plus the summary block. It does not characterize the summary block's remaining contents or the empty-state response, which leaves a small gap for a parameterless reporting 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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description instead spends its words on output semantics, which is the right allocation for a parameterless read.

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 names a specific resource (active Morpho yield positions) and enumerates the per-vault fields returned (valueUsd, earnedUsd/netApy, summary block), which implicitly separates it from market-listing siblings like list_yield_markets. It stops short of explicitly naming the sibling it is not, so it lands at 4 rather than 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?

"Use at the start of every yield desk run to report standing P&L" gives a concrete trigger condition and a stated goal, which is clear usage context. There are no exclusions or named alternatives (e.g., get_portfolio, list_strategies) for an agent that wants a broader position view, so it is not a full when/when-not treatment.

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