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

Annotations already declare readOnlyHint and idempotentHint, and the description adds useful behavioral context: it works across 300+ markets, returns a snapshot with a DCPI verdict and last_updated timestamp, and is scoped to a single market. It does not mention the MPP/autopay challenge flow, but those details are fully described in the input schema and do not contradict the annotations.

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 front-loaded with the main use case, then gives an example, param explanation, return shape, and exclusion routing. The return-structure section is somewhat redundant with the output schema, but the organization is clear and each section earns its place without excessive verbosity.

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?

For a tool with rich annotations and a full input/output schema, the description covers the essential selection and invocation context: use case, example call, market slug format, and sibling routing. It could have mentioned compare_to or the MPP payment parameters at the top level, but those are well-documented in the schema, so nothing critical is missing for correct normal usage.

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 description coverage is 100%, so the baseline is 3. The description adds an example invocation and clarifies that market is a market_slug, but metric, period, compare_to, and payment parameters are left entirely to the schema. This is adequate but does not go beyond the schema in a meaningful way.

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 explicitly states the tool is for ONE data-center market and lists the concrete metrics returned (vacancy, capacity pricing, supply pipeline, dominant operators, YoY growth). It also differentiates itself from rank_markets and get_facility, making the tool's purpose immediately clear.

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?

It gives an explicit when-to-use condition ('Use when a user asks about ONE data-center market') and explicit when-not-to-use guidance with named alternatives ('Do NOT use to rank multiple markets (use rank_markets) or for a single facility (use get_facility)'). This is strong routing that leaves little to inference.

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