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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered and the repeated 'Read-only' is redundant. The description still adds real behavioral scope: the tool is conditioned on DEX/aggregator transactions and limited to EVM chains, and it explains the interpretive output ('flag who the swap was actually for'). It does not describe failure behavior for non-swap inputs.

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?

Three tight sentences, front-loaded with the core behavior, then usage, then scope, then a safety note. No filler or restatement of the tool name.

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?

With no output schema, the description usefully sketches what comes back (per-address, per-asset net balance delta plus a 'who was the swap for' flag) and the chain scope. The only gap is how it behaves on a transaction that never touched a DEX or aggregator.

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% with only 3 simple parameters (tx_hash, chain, optional block_number), so the schema already carries the parameter burden. The description adds no syntax, format, or resolution details beyond what the schema states, matching the baseline of 3.

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 ('show the net balance change per address and asset') plus the trigger condition ('one transaction that went through a DEX or aggregator'), which separates it from the broader trace_funds/trace_source_of_funds siblings. An agent can tell what this does without opening the 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?

'Use it to continue a trace past a swap' ties usage directly to the trace family, and the EVM chain constraint (ethereum, bsc) narrows applicability. No explicit when-not or guidance on what to do for non-DEX transactions, so it stops just short of a 5.

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