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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=true, so the safety profile is covered upstream. The description adds something annotations cannot: 'Rates change; the numbers are a snapshot,' which warns the agent the returned values are point-in-time and must not be cached or treated as authoritative. It also defines the data universe (USDG vaults, stock-token collateral markets), which bounds expectations about world-open results.

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?

Three short sentences, front-loaded with the resource and its returned fields before the invocation note. The opening sentence is dense with field names but every clause maps to something the caller needs. No filler or marketing language.

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 carries full burden for return values and does so by naming the fields (net APY, size, curator, borrow rate, LLTV) and the two result categories. For a zero-required-parameter read tool this is close to sufficient; only the response shape (grouping, ordering, coverage when ticker is empty) is unspecified.

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 description coverage is 100%, and the schema already states the ticker accepts a symbol or token address and that empty lists all stock-token markets. The description's 'Pass a ticker for one stock' restates that in shorter form without adding format, casing, or fallback behavior. Baseline 3 applies since the schema carries the detail.

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 (Morpho on Robinhood Chain) and enumerates exactly what it returns: USDG vaults with net APY, size, curator, plus lending markets accepting stock tokens with borrow rate and LLTV. That is enough to separate it from action-oriented siblings like build_morpho_deposit and morpho_loop, though it never explicitly says 'this is the read-only lookup, not the builder'.

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 only usage direction is 'Pass a ticker for one stock,' which is really an invocation note rather than when-to-use guidance. There is no statement of the workflow position (e.g., call this before building a deposit with build_morpho_deposit) or of when to prefer the unfiltered listing. Usage is implied by the noun 'rates' but not spelled out.

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