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

Annotations already declare destructiveHint=true and readOnlyHint=false, and the description adds the useful precondition 'Requires need_approved=true'. However, it does not disclose other behaviors such as whether the transaction is only signed or also submitted, or what side effects signing has beyond the implied state change. The added context is helpful but not rich; with annotations covering the safety profile, this is adequate but not exceptional.

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 a single, front-loaded sentence that begins with a '[write]' tag and immediately states the action. Every word contributes: the operation, the target, the context, and a key prerequisite. There is zero redundancy or 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?

The description is adequate for a tool in a multi-step swap flow, but it lacks explicit guidance on what to do after signing or how this step fits with siblings like dex_tx_swap_submit. The schema partially compensates by referencing the prepare and checkin steps. Given the complexity of the flow, a mention of the next step would improve completeness, but it is not critically incomplete.

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 parameters are already documented in the schema, including the checkin_token and swap_session_id sources. The description itself adds no parameter-specific meaning beyond the need_approved condition, which is not a parameter. This meets the baseline for high coverage but provides no extra value.

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 tool's function: 'Sign the ERC20 approve tx for a staged EVM swap.' This uses a specific verb ('sign'), a specific resource ('ERC20 approve tx'), and distinguishes it from sibling tools like dex_tx_swap_sign_swap and dex_tx_swap_submit. The additional prerequisite (requires need_approved=true) adds precision without ambiguity.

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 provides clear context for when to use the tool: it is for signing the approve transaction in a staged EVM swap, and specifically requires need_approved=true from the prepare result. This implies it is not for the swap signing itself, though it does not explicitly name alternatives or exclusions. The stated precondition offers actionable usage guidance.

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