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

Goes well beyond the annotations by disclosing the pricing model ($0.001 per call), the exact endpoint and method (GET /kv/list), the fact that it returns the paid x402/MPP request rather than the data itself, and that invalid input is refused before any charge.

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?

Front-loads the use case, then packs scope, cost, and next-step mechanics into two tight sentences with no 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?

With no output schema, the description still explains what the call returns (the paid request, response schema, and an example) and how to complete it, leaving nothing an agent needs unstated.

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 coverage is 100%, so the schema already documents limit, cursor and prefix; the description only restates the 100-key ceiling and the optional prefix filter, adding no syntax or edge-case detail. Baseline 3 applies when the schema carries the weight.

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 ('lists up to 100 keys ... in the namespace of the paying wallet') plus the returned fields (size, stored_at, expires_at), which distinguishes it from kv_get and kv_put without needing to name them.

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 when an agent needs to see what it has stored' gives an explicit triggering condition, and the payment note implies it is a paid discovery step before actual retrieval. Sibling alternatives such as kv_get are not named, so it stops short of full routing guidance.

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