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

Annotations declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false. The description adds context beyond annotations: it builds an unsigned transaction (not submitting), it explains the eMode concept and its tradeoff, and it notes that v4 replaces eMode. It doesn't explicitly say 'this does not submit a transaction', but 'Build an unsigned transaction' implies that. The description is consistent with annotations and adds meaningful 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 compact and front-loaded: it opens with 'v3 only' and the core action, then explains the eMode concept in one sentence, then gives the two key usage instructions (take categoryId from get_emode_categories, pass 0 to disable), and closes with the v4 exclusion. Every sentence earns its place; no filler.

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 transaction-building tool with no output schema, the description covers the essential context: what the tool does, how to get the required categoryId, how to disable eMode, the version constraint, and the v4 alternative. The schema covers parameter details, and annotations cover safety. An agent has enough to select and invoke this tool 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 the schema already documents all parameters. The description adds value by explaining the semantic meaning of categoryId (from get_emode_categories, 0 to disable) and the market constraint (v3 only, from a get_markets row, cannot be recalled). It also clarifies the version parameter is optional and only 'v3'. This goes beyond the schema's field-level descriptions.

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 specific verb ('Build an unsigned transaction'), a specific resource ('Aave v3 eMode category'), and the exact scope ('v3 only'). It also explains what eMode does (groups correlated assets, higher LTV, borrowing power vs. asset restrictions), which distinguishes it from generic prepare_* siblings. The phrase 'v3 only' is repeated, reinforcing the version constraint.

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 this tool: to switch a wallet's Aave v3 eMode category. It tells the agent to take categoryId from get_emode_categories, and to pass 0 to turn eMode off. It also explicitly excludes v4 ('v4 replaces eMode with risk premium and dynamic config'), which is a clear when-not-to-use signal. This is strong guidance.

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