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

With no annotations, the description carries the burden. It discloses a critical limitation ('this server cannot sign') and auth requirements, but does not explain side effects like replacing existing auto-topup config, impact on balances, or behavior when authorizations are spent or expire. The provided constraints are useful but incomplete.

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?

A single, dense sentence packs the core purpose, trigger condition, key restriction (no signing), and auth requirement. Every clause earns its place, and it is front-loaded with the action. No filler or redundancy.

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 covers the trigger and input but omits post-configuration behavior (e.g., confirmation, how to check existing config via get_auto_topup, or whether settings are replaced). Since there is no output schema and no annotations, a little more context about effects and verification would improve completeness, though it is adequate for a straightforward config tool.

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?

The schema has 100% coverage, so a baseline of 3 applies. The description adds meaning by explaining that 'threshold_usd' triggers the top-up and that 'authorizations' are pre-signed payloads used for settlement. It does not elaborate on 'max_per_month' but that is adequately described in the schema. Overall, it enhances understanding beyond the raw schema.

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 opens with 'Configure auto-topup', specifying the exact action and resource. It then explains the trigger condition (balance below threshold) and the mechanism (pre-signed EIP-3009 authorizations), which clearly distinguishes it from siblings like get_auto_topup, remove_auto_topup, and topup_balance.

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 conveys when the tool is used (when configuring automatic refills) and includes a key prerequisite ('Auth required' and the need for pre-signed authorizations). It does not explicitly list alternatives, but the context of configuring vs. manual top-up (topup_balance) is implied.

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