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

Beyond the annotations (readOnly, openWorld, idempotent, non-destructive), the description adds important behavioral context: unknown IDs return 'not_found_or_unpublished', geographic coverage (Coimbatore and Chennai), output semantics (pricePerSqft, vsCheapestPercent, vsLargestAreaPercent), and a user-facing requirement ('Always surface the disclaimer'). This significantly enriches the agent's understanding of the tool's behavior.

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?

The description is compact yet information-dense, with each sentence adding value: purpose, prerequisite, edge-case handling, output fields, scope, and limitations. It is front-loaded with the core function and avoids redundancy, making it easy to process.

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?

The description covers key contextual aspects: prerequisites, error behavior, geographic scope, output semantics, selection strategy for many candidates, and a disclaimer requirement. Given that an output schema exists, the description need not repeat return types, but it still adds meaningful context like 'not_found_or_unpublished' and the meaning of comparative percentages, making it highly 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 fully describes the only parameter (listingIds), including its purpose, constraints, and source (from search_properties). The description adds little beyond restating that IDs are not guessable and listing the count range, which the schema already covers. With 100% schema coverage, a score of 3 is appropriate—the description doesn't introduce new parameter semantics.

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 clearly states the tool's function: 'Compare 2–5 AVnester listings by listingId, side-by-side.' It specifies the verb (compare), resource (AVnester listings), and method (by listingId, side-by-side), distinguishing it from siblings like search_properties (which returns listings) and compare_localities (which compares localities).

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 provides explicit guidance: 'Get IDs from search_properties first (not guessable)' establishes a prerequisite and alternative. It also addresses when not to use the tool ('Does NOT recommend a purchase') and how to handle over 5 candidates ('pick the most relevant 5... and say so'). This clearly instructs when and how to invoke the tool, including exclusions.

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