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

Annotations only cover the safety profile (read-only, idempotent, open-world), while the description adds genuinely useful behavior: spam filtering is applied, the data comes from Covalent, the address is Base-scoped, and the call is paid ($0.02 per call over x402, prepaid x-credit-token header for unlimited calls, no free tier, no API key required). Cost and auth mechanics are exactly what an agent needs and are not in the structured fields.

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 purpose, then scope, then payment terms; each sentence carries information. The opening 'NFT collections held by a wallet (+ floor)' mildly duplicates the sentences that follow, which is the only real waste.

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 described. Chain scope, spam filtering, data source, single required input, and full payment/auth requirements are all covered, leaving nothing an agent needs missing before calling.

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% and the single 'address' parameter is documented in the schema, so the description's 'Required input: address' adds little. It does not add any format or syntax guidance (e.g., checksumming or Base-specific address handling), so the baseline of 3 is appropriate.

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 NFT collections held by a wallet), plus chain scope (Base), returned fields (name, count, floor value) and data source (Covalent). This is clearly distinguishable from near siblings like nft_floor or wallet_tokens.

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?

Gives an explicit use case ('For agents profiling a wallet's NFT exposure') and names the required input, which sets the context for invocation. It does not, however, name alternatives such as nft_floor for per-collection floor data or wallet_tokens for fungible holdings, so the when-not-to-use side is left to inference.

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