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

Annotations already establish read-only, non-destructive behavior, and the description reinforces this with 'without building anything.' It adds meaningful behavioral context beyond annotations by disclosing that the vault index is live and moves, explaining the unit-of-amount asymmetry, and warning that a GHO figure in a withdraw would withdraw the wrong amount. This is exactly the kind of context an agent needs.

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 dense sentences, each serving a purpose: constraints, core behavior, unit semantics, and call-order/rate warnings. Front-loaded with 'v3 only, Ethereum only,' and no filler. The one mild redundancy with the version schema is negligible.

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?

For a read-only preview tool with two required parameters and no output schema, the description fully specifies both action directions, the correct amount denomination, the prerequisite ordering for withdrawals, and why not to use a static rate. An agent has everything needed to invoke it correctly.

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%: the action and amount properties already state which unit applies to each action. The description restates this relationship but does not add new parameter-level meaning beyond the schema; it merely reinforces what is already documented.

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 states a precise verb ('Convert') and resource (GHO/sGHO shares at the vault's current index), and explicitly disclaims building actions: 'without building anything.' It also distinguishes itself from sibling prepare_sgho_action by instructing when to call it for withdrawals, making the tool's unique role unmistakable.

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?

Provides explicit when-to-use guidance: 'Call this with action withdraw before prepare_sgho_action' and 'When quoting what a user-named amount converts to, use this preview rather than multiplying by the rate.' It names the incorrect alternative (multiplying by the rate) and explains why it fails: 'the index moves.'

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