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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds meaningful behavior beyond those annotations: it requires an API key on the Investor plan and provides explicit URLs for pricing and key creation. It also documents the 'no filters returns national top-ranked markets' behavior, which is useful and non-obvious.

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 and front-loaded with the core behavior, followed by auth requirements and a useful example. The two URLs are somewhat clunky but earn their place because they provide necessary setup instructions. No filler sentences are present.

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 six optional parameters, a complete input schema, an output schema, and safety annotations, the description covers the essential operational details: ranking behavior, national default, API key requirement, and a representative parameter combination. Nothing critical is missing for an agent to select and invoke the tool correctly.

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 input schema already documents all six parameters with descriptions and defaults, so schema coverage is 100%. The description contributes a practical example state='TX', max_price=300000, min_rental_yield=6, but it does not add new semantic meaning beyond what the schema already provides. Baseline 3 is appropriate.

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 states a specific action and resource: 'Rank US markets by investment criteria.' It also clarifies that omitting filters returns top-ranked national markets, which distinguishes it from a simple listing tool. However, it does not explicitly name or differentiate against sibling tools like list_markets, so it falls just short of the strongest clarity.

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 implies when to use the tool: when you want markets ranked by investment criteria, optionally filtered by state and metrics. It gives a concrete example, but it does not explicitly explain when to prefer compare_markets, get_market_health, or list_markets instead. No exclusions or alternative routing is provided.

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