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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered; the description adds the genuinely non-obvious operational fact that each call costs $0.60 USDC via x402 on Base or Solana. That payment/auth detail is exactly the kind of context annotations cannot express, though rate limits, timeout or failure behavior are not mentioned.

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, front-loaded with the return payload and the question it answers, with the price disclosure isolated at the end. The long enumeration of metrics is justified rather than padding, since no output schema exists to carry that information elsewhere.

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 and no parameters, the description carries the full burden of telling the agent what comes back, and it does so metric by metric, including the analytics assumptions (20% down, 28% DTI). The one gap is data recency — median sale price series like MSPUS are lagged, and calling this to answer 'today' without a freshness note could mislead.

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 tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description correctly presents this as a parameterless pull, matching the empty input 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 a precisely enumerated resource: 'Returns a home purchase market bundle' followed by the exact six metrics it contains (30yr rate, MSPUS, monthly P&I, qualifying income, affordability signal, housing starts). The contents also differentiate it from siblings like get_bundle_mortgage_pulse and get_bundle_refi_signal, which are narrower rate-only bundles.

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?

Frames the decision it supports — 'can my client afford a home today?' — which tells the agent the buyer-affordability scenario that selects this bundle. There are no explicit exclusions or comparisons against the other bundle siblings (mortgage_pulse, refi_signal, rate_environment), so the agent must infer which bundle wins in overlapping cases.

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