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

Goes well beyond the annotations: discloses error handling ('malformed address or slot is rejected with 400, uncharged'), cost model ($0.01/call via x402 USDC or card key, first 25 free, failed calls free), and clarifies that repeats are charged — which explains the idempotentHint=false flag. Also confirms read-only semantics ('reads or computes only and changes nothing'), consistent with readOnlyHint=true.

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-loaded with the core action and return shape, then usage, then errors, then pricing. Dense but mostly purposeful; the pricing/auth sentence is long and reads partly as boilerplate, keeping it from a 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?

With no output schema, the description fully carries the burden: it specifies return values (word as number plus address when applicable), error behavior, cost, and safety profile. Nothing an agent needs to invoke it correctly is missing.

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 adds real value: it explains that a 0x 32-byte slot key is used for mapping and proxy slots and gives a concrete address example. Only slightly above baseline because the decimal-vs-hex distinction is already in the 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?

States a specific verb and resource ('Read one raw storage slot of a contract on Mantle') and names the underlying RPC (eth_getStorageAt), including the return shape (32-byte word as number, address when applicable). It also distinguishes itself from the sibling family by pointing proxy introspection to mantle_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 names the alternative for the proxy case ('for proxies use mantle_proxy'). An agent can route between mantle_storage, mantle_proxy, and mantle_call without opening schemas.

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