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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds real value beyond them: pricing ($0.01/call, first 25 free, failed calls free), 400 rejection behavior for malformed input that is uncharged, and the fact that repeated calls are charged — which explains the idempotentHint=false annotation rather than contradicting it. Slightly short of 5 only because it does not touch on rate limits or response shape beyond the word/address note.

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 core operation and return shape, then layers usage, error behavior, example, and pricing. Dense but every clause carries information; the pricing/payment detail is long but material for a paid x402 endpoint. Minor density cost keeps it from 5.

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?

No output schema exists, and the description compensates by stating what comes back (numeric word plus address when applicable). Combined with error behavior, pricing, and usage routing, an agent has everything needed to decide and invoke correctly for a 2-parameter read 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?

Schema coverage is 100%, so the baseline is 3, but the description earns more by clarifying the slot's two forms in context (decimal index or 0x 32-byte key, explicitly noting mapping and proxy slots) and giving a concrete address example. It adds semantic meaning the schema strings alone do not convey.

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 ('Read one raw storage slot of a contract on Sei'), names the RPC equivalent (eth_getStorageAt), and specifies what is returned (32-byte word as number and, when applicable, as address). This clearly separates it from sei_call and sei_proxy.

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?

Explicitly states when to use it ('inspect contract state that has no getter, owners or implementation pointers') and routes proxy cases to sei_proxy as the alternative. Both the use case and the sibling hand-off are stated rather than inferred.

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