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

Goes well beyond annotations to disclose pricing ($0.005/call), the payment rail (USDC on Solana via x402), and the exact MCP invocation dance (call to get PaymentRequired, retry with payment at _meta['x402/payment']). This is exactly the operational context an agent needs for a paid tool.

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 purpose and constraint, then the payment mechanics. Dense but each clause earns its place—pricing and the x402 retry flow are non-negotiable for a paid endpoint. Slightly heavy on payment prose but not wasteful.

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 correctly states the return format (SVG). Combined with the byte limit, pricing, and payment flow, an agent has what it needs to call it correctly; only explicit size behavior is left implicit.

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 the 106-byte cap that isn't in the schema's 'Text to encode' field, and returning SVG implies the size param governs output dimensions. Adds measurably more than the schema alone.

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 resource and output format ('QR code as SVG') plus a concrete constraint (max 106 bytes of text). It's unambiguous what the tool produces, though it doesn't explicitly contrast with any devutils sibling since none is a near-equivalent.

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?

The 106-byte limit and payment flow imply invocability constraints, but there's no 'use this when / not when' guidance. The payment retry instructions tell you how to call it, not when to prefer it over alternatives.

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