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

Annotations only declare it as a non-read-only, non-idempotent, open-world mutation, and the description adds substantial context on top: it does NOT sign or broadcast, the user signs, steps consist of ~10 bps ETH fee, approve, and swap, v4 adds a Permit2 approval, and a v4 plan expires after 30 minutes. These are exactly the behavioral traits an agent cannot infer from the annotations.

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?

Five short sentences, front-loaded with the core action and chain, then venue logic, then steps, then the critical non-signing constraint, then expiry. Every sentence carries distinct information and none restates the tool name or annotations.

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 9-parameter mutation tool with no output schema, the description covers composition, prerequisites, and lifetime well enough to call it correctly. It could have gone further by describing the shape of the returned plan (what fields an agent should surface before the user signs), which is the remaining gap.

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 every parameter (owner, tokenIn/Out, slippageBps default, notionalUsd policy check, approveMax) is already documented at the field level. The description adds no parameter-level syntax or format guidance beyond the schema, so the 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 and resource ('Build an unsigned swap plan on chain 4663') plus the mechanism for venue selection (higher amountOut among v4, v3, 0x, Uniswap API). An agent immediately knows this produces a plan rather than executing a swap. It does not explicitly contrast itself with siblings like stocktoken_quote or stocktoken_simulate, so it stops short of a 5.

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?

Usage is implied rather than stated: the description explains what the plan contains but never says when to prefer this over stocktoken_quote, stocktoken_simulate, or stocktoken_intent_typed_data. It does surface one real precondition ('Pro required') and one operational constraint (v4 plan expires in 30 minutes), which lifts it above a bare 2.

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