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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, so the bar is lower. The description adds genuine context beyond that: the data is verified month by month against MLS statistics, and the returned history is asymmetric by island (Kiawah and Seabrook reach back to 2021-01-01, others apparently do not). It does not discuss latency, caching, or refresh cadence.

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, but both are long run-ons built from colon-delimited clause stacks listing metrics. The island/time-range scoping is front-loaded, which helps, yet the metric inventory in sentence two reads as filler given an output schema already exists.

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 an output schema present, the description need not enumerate return fields, and it sensibly focuses on scope, provenance, and per-island time ranges. The one-parameter schema is fully documented. Minor gap: it never states what Johns Island actually returns, only that it lacks the Kiawah/Seabrook extras.

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 enum is fully described, so baseline would be 3. The description goes further by explaining that the island choice materially changes the payload: Kiawah and Seabrook add multi-year history and extra metrics, while Johns Island does not. That is real selection-relevant meaning beyond the enum labels.

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 names a specific resource and scope: 12 months of residential sales statistics for Kiawah, Seabrook or Johns Island, drawn from the MLS's own figures. It lacks an explicit verb (no 'get'/'return') and never contrasts itself with siblings like estimate_range or true_cost, so an agent must infer that this is a read of aggregated market metrics rather than a valuation tool.

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?

There is no statement of when to use this tool, when not to, or which sibling to prefer for related questions (estimate_range, true_cost, get_neighborhood all sit in adjacent territory). The only implicit guidance is that the tool is island-scoped market data, which is not enough to route between siblings.

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