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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and openness are covered. The description adds that the estimate is 'public' and lists the returned content categories, which is useful. However, it says nothing about freshness/lag of the estimate, rate limits, or whether property_id must come from Redfin. Annotations carry the safety load, so a 3 is appropriate for the added but limited behavioral context.

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 tight sentences: the first states the action and the full return payload, the second routes the agent to the correct sibling tools. Front-loaded with the key verb and resource, no filler, every clause earns its place.

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 needn't retell return structure, and it correctly stops at naming the content categories. It covers obtaining the required ID and alternative tools. The only minor gap is behavioral specifics like estimate freshness or rate limits, but for a read-only estimate lookup this is close to 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?

There is one parameter with 100% schema description coverage ('Required Redfin property id.'). The description reinforces that it's a Redfin-specific ID and points to sibling tools for finding one. Beyond that, it adds no format or syntax detail not already in the schema. Baseline 3 for high schema coverage is correct.

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?

Specific verb+resource: 'Fetch the public Redfin Estimate for property_id', followed by an explicit enumeration of the returned content (property facts, monthly estimate history, city/county/postal comparisons). This distinguishes it cleanly from redfin_property (raw listing) and redfin_region_trends (aggregate trends).

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?

Explicitly names three sibling tools (redfin_search, redfin_property, redfin_similar, redfin_region_trends) and the condition for each ('to find an ID', 'for comparable listings', 'for regional data'). The agent knows exactly how to obtain the required property_id and when this tool is not the right one.

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