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

Adds real context beyond the annotations: this does not fill, it returns an approval link and the user signs in the Epsilon app. That is critical behavioral knowledge an agent could not infer from readOnlyHint=false / openWorldHint=true. It stops short of covering approval-link lifetime, non-idempotency (annotations say idempotentHint=false but the description doesn't warn that retries create duplicate requests), or fund/slippage exposure.

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 short sentences, each carrying distinct load: action, return semantics, prerequisite, alternative. The non-fill caveat is front-loaded right after the action, which is exactly where an agent needs it.

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?

No output schema exists, yet the description compensates by explaining what actually comes back (an approval link) and who completes the flow (the user in the Epsilon app). Combined with the get_quote prerequisite and sibling routing, an agent has everything needed to call this 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%, including the 'HUMAN units' note for amount, so the description's 'Amounts are HUMAN units' restates the schema rather than adding to it. None of the five parameters (note, slippageBps, token addresses) get supplemental meaning in the prose. Baseline 3 applies.

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?

States a specific verb+resource ('place a market swap of amount tokenIn → tokenOut') with the execution venue ('best current route'), and explicitly contrasts itself with the price-conditional siblings. An agent can distinguish this from place_limit_order/place_stop_order without opening any schema.

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?

Gives an explicit prerequisite ('Use get_quote first to tell the user what to expect') and an explicit routing rule away from the tool ('For a price-conditional order use place_limit_order or place_stop_order'). When-to-use and when-not are both covered.

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