discover_brand_domains

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

Annotations declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, which description fully supports. Description adds behavioral details: aggregation of multiple signal types, two discovery modes (classic/tiered) with explanations of each, caching behavior with force_refresh, and ownership_verified requirement for tiered mode. No contradiction.

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?

Extremely concise: two sentences plus one critical warning. Front-loaded with purpose and usage. Every sentence adds value; no fluff. The warning about seed domain is bolded in the original, drawing attention.

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 12 parameters and an output schema, the description covers core purpose, key behavioral constraints (seed domain handling), two discovery modes with their differences, and prerequisites (ownership_verified for tiered). It does not explain return format (handled by output schema) and assumes some domain knowledge, but is complete for its complexity level.

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 baseline is 3. Description adds value by reinforcing the critical constraint for the domain parameter ('Do NOT normalize...') and elaborating on discovery_mode and ownership_verified. However, most parameters already have clear schema descriptions.

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?

Description explicitly states the verb 'discover' and resource 'brand's portfolio domains', and distinguishes from sibling tools like discover_subdomains by focusing on brand portfolio rather than subdomains of a single domain. It also clarifies usage context: 'Use when asked what domains are part of a brand portfolio'.

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?

Provides clear when-to-use guidance and a critical directive: 'Pass the EXACT seed domain verbatim — do NOT normalize'. Mentions brand_aliases for related labels. Lacks explicit mention of when not to use this tool or alternative siblings for other tasks (e.g., subdomain discovery), but the sibling list provides those alternatives.

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