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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely non-obvious context: the data is a public profile and the call consumes 1 credit, which matters for budgeting against siblings. It stops short of describing failure modes or how much of the profile is populated for partner agents.

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?

Three short sentences, resource first, payload second, cost last. Zero filler; every sentence carries information an agent can act on.

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 does the necessary work by naming the fields returned, and the credit cost is disclosed. For a simple, read-only single-record lookup this is nearly complete; only the semantics of the two undocumented auxiliary parameters are missing.

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%: url and tld are documented in-schema (including a concrete example URL), but country_code and cache_max_age have no description anywhere and the description does not fill that gap. The required parameter is unambiguous, so baseline 3 applies, but no value is added beyond the schema.

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 resource ('Real estate agent profile') and enumerates the returned fields (name, brokerage, contact, bio), which clearly separates it from redfin_search / redfin_forSale / redfin_forRent and signals it parallels zillow_agent. It does not explicitly name a sibling it differs from, so it stops short of a 5.

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 implied: fetch a single agent profile given a profile URL. There is no explicit statement of when to prefer this over zillow_agent for the same agent, nor any prerequisite or constraint (e.g. 'URL must be a profile page, not a listing page').

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