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

Annotations already declare readOnlyHint=true and openWorldHint=false. The description adds real behavior beyond that: results are limited to the 4ai portfolio and it explicitly reports when a domain isn't in it, which shapes how the agent interprets an empty/unhelpful response.

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, front-loaded with the core purpose, followed by the returned-field list and the negative case. No filler or redundancy.

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, listing the returned fields is the right compensatory move, and the not-found behavior is covered. Minor gaps remain (what 'page' and 'offer link' actually contain), but an agent has enough to call it 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?

Schema coverage is 100% and the schema already says the name is accepted with or without '.ai'. The description's only addition is a concrete example ('p0.ai'), so it neither compensates for nor exceeds what the schema provides — baseline 3.

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 verb+resource: fetch details for one domain in the 4ai portfolio, and enumerates the returned fields (categories, page, offer link, comparable public .ai sales). That scope is clearly distinguishable from siblings like search_domains, list_categories, ai_domain_sales, and estimate_domain_value.

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 by the single-domain, portfolio-scoped framing, and the not-in-portfolio case is handled. But it never states when to prefer a sibling (e.g., use search_domains to find a domain, or estimate_domain_value for a valuation), so the agent must infer the routing.

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