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

With no annotations, the description carries the full burden and largely meets it: it marks the tool as free, discloses tier pricing, per-tier rate limits and history windows, and explains the USDC-on-Base payment and key-activation flow. It stops short of stating explicitly that calling this tool has no side effects and makes no subscription itself, and the embedded subscribe/pull endpoint instructions blur whether the tool performs those actions.

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 dense but not front-loaded — the one sentence that actually defines the tool ('This tool returns plan info and terms') appears only after a long promotional lead-in. Roughly half the text is HTTP endpoint and URL documentation that belongs in linked docs and risks misleading the agent into thinking it should issue those requests itself.

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?

An output schema exists, so return values need not be explained, and for a zero-parameter info tool the pricing, tiers and monetization model are adequately covered. The only gap is the lack of an explicit statement about what happens when the tool is invoked (read-only, no cost, no subscription created).

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 tool takes zero parameters with a fully closed schema, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description correctly implies no input is needed.

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 identifies the resource (AgentWorld Economy Data Feed) and states mid-way that 'This tool returns plan info and terms,' which is a specific verb+resource pairing. However, it never distinguishes itself from sibling data tools such as data_economy or get_economy, so an agent must infer that this one is a pricing/terms tool rather than a data-retrieval tool.

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: call this to learn plans and terms, then use the described HTTPS endpoints to subscribe and pull data. There is no explicit statement of when NOT to use it or which sibling to prefer for the actual economy data, leaving the agent to infer the boundary.

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