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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the read-only nature is covered. The description adds meaningful context beyond annotations by disclosing that this is a 'Premium API' costing $0.25 USDC via x402, which is critical for an agent deciding whether to call it. It also enumerates what data is returned, adding behavioral expectations. It doesn't mention rate limits or failure modes, but with annotation coverage that's a minor gap.

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?

Two sentences, both information-dense. The output list in sentence one is long but every item is a specific data point an agent would want to know, and the cost disclosure in sentence two is essential. No filler or repetition.

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's detailed enumeration of the returned data (last sale, prior transactions, ownership chain, deed types, mortgage history) serves as the output specification, which is good. It also covers the cost prerequisite. It doesn't discuss potential edge cases (unrecognized address, US-only constraints), but these are adequately implied by 'any US address' and the read-only annotations. Given the simplicity (1 param) and annotation coverage, this is nearly complete.

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?

The schema already fully describes the sole address parameter with an example and explanation (100% coverage). The description only adds the phrase 'any US address,' which does not materially expand the meaning beyond the schema. Baseline 3 applies since the schema is doing the heavy lifting.

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?

The description opens with a specific verb and resource: 'Retrieve property transaction history for any US address'. It enumerates the exact data included (last sale date/price, deed types, mortgage history, etc.), making it unmistakable from siblings like building_profile or address_parse. This is a textbook clear purpose.

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 description defines the clear use case: property transaction history for a US address, and even constrains it to any US address. It does not explicitly name alternative tools or provide when-not-to-use guidance, so while context is clear, there's no explicit differentiation from siblings.

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