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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering safety. The description adds value beyond that: it specifies 'v3 only', describes the output structure (total yield plus per-sample breakdown), and explains the window buckets (no day or six months). It does not contradict annotations and provides useful behavioral context.

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 key constraint ('v3 only') and purpose. Every sentence earns its place: purpose, differentiation from APR, and prerequisite guidance. No fluff or redundancy.

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 5-parameter tool with no output schema, the description is remarkably complete. It explains what is returned (total yield and per-sample breakdown), the window buckets, the version restriction, and where to get required inputs. The complexity is low but the description covers all essential aspects an agent needs 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%, so all five parameters are documented in the schema. The description adds nuance beyond the schema: it clarifies the window enum has only specific buckets and warns against expecting others, and it reiterates the v3-only constraint. This goes beyond a baseline of 3 by enriching parameter understanding.

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 verb and resource: 'How one wallet's position in one vault moved over a window', with specific outputs (total yield, per-sample breakdown of balance, deposits, withdrawals). It explicitly distinguishes from the APR concept, which is a different metric, and mentions get_vaults as the source for required inputs, differentiating it from other history tools.

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 explicitly says when to use it: to answer 'what has this vault actually paid me', contrasting with the current APR which is not the same. It also notes that the vault address and chain come from get_vaults. However, it does not explicitly name alternative tools like get_apy_history or get_user_activity, though the context implies them.

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