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

Annotations already cover read-only, idempotent and non-destructive, so the description is free to add the value it does: the exact fields returned, the 'unknown where the listing is silent' data-completeness caveat, and the optional match-score mode. It stops short of stating result ordering or output shape, but goes meaningfully beyond the structured hints.

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?

A single front-loaded sentence ('Side-by-side comparison of 2-5 properties...') followed by the dimension list and the optional watchlist clause. The dense clause list is long but each item is load-bearing, since there is no output schema to carry the compared fields.

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 must convey what comes back, and it does so by enumerating compared dimensions plus the unknown-when-silent caveat. Read-only behavior is covered by annotations, so the remaining omission — result ordering or uncertainty about duplicate ids — is minor.

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 50% — property_ids has no inline description. The description compensates by naming 'property_id' and bounding the count to 2-5, and it explains the watchlist parameter as scoring each property against a saved search, which matches and enriches the schema's terse one-liner.

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 (compare) and resource (properties) with the exact scope of 2-5 items and the dimensions compared (price, size, age, HOA, etc.). It is clearly distinguishable from siblings like get_property_details or analyze_property_investment by the multi-property side-by-side framing, though it never names an alternative to route against.

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?

Usage is only implied: the '2-5 properties' constraint tells the agent the batch size, and the optional watchlist clause hints at the scoring use case. There is no explicit when-to-use vs when-to-pick-get_property_details/analyze_property_investment guidance.

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