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

Adds substantial context beyond the annotations: unknown hash returns 404 uncharged, failed calls are free, each call is charged so repeats are not free, and pricing via x402 USDC or card key with 25 free calls — which usefully explains the idempotentHint=false. The closing 'reads or computes only and changes nothing' mostly restates readOnlyHint/destructiveHint=false, which is the only redundant part.

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 purpose, then alternatives, then input format, example, and pricing in a compact block with no wasted sentences. The trailing safety/pricing sentence is dense and partly duplicates annotation semantics, keeping it just short of ideal.

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?

For a single-parameter read tool with no output schema, the description covers the return fields, input format with example, error/404 behavior, and cost model. Combined with annotations already declaring the safety profile, an agent has everything needed to call it correctly.

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 schema already documents the 0x-prefixed 64-hex format, so the baseline is 3. The description goes slightly further by supplying a concrete example hash and stating the 404 behavior for unknown hashes, adding marginal value beyond 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 ('Look up a Polygon PoS transaction by hash') and enumerates the returned fields (sender, recipient, value in POL, nonce, gas limit, function selector, block), so the agent knows exactly what it gets. It also distinguishes itself from polygon_receipt and polygon_logs by name.

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 explicit when-to-use guidance ('Use to see what was sent or whether it exists') and names the two alternative tools with the conditions that select them (success/failure and fees → polygon_receipt; emitted events → polygon_logs). Nothing 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.