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

Annotations already declare readOnly/idempotent/no-destructive, so the bar is lower, yet the description adds substantial non-obvious behavior: separate 20-item pages for URLs and history, independent cursor chaining, cursor/scope token agreement, and the staleness rule that new completed Scans do not extend continuation and you must restart after metadata edits or evidence repairs.

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?

Dense but front-loaded, opening with the core action before pagination and scope mechanics. Nearly every sentence carries operational signal, though the run of cursor/staleness rules borders on over-packed for a single block.

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 15-parameter, low-coverage-schema tool with an output schema available, the description discloses the pagination model, scope inheritance, staleness, empty-success semantics, and field-level return nuance (date vs completedAt, subjectContext null for legacy) without redundantly restating return values.

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 27%, so the description must compensate and largely does for the tricky parameters: the urlNextCursor→urlCursor and trendNextCursor→trendCursor mapping, scopeToken inheritance, and the domain key constraint. The remaining filter parameters (tag, region, persona, product, etc.) are covered only implicitly via 'repeat its filters'.

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 and resource ('Read one exact domain') and explicitly positions it as a drill-down from get_references, naming the source of the domain key. An agent can distinguish it from get_references and from sibling list/get tools without opening the schema.

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?

Gives clear selection guidance: pass the overview scopeToken and repeat filters to inherit the evidence boundary, or omit for a standalone scope, plus explicit exclusions ('No URL fetching or Scan launch'). It names get_references as the prerequisite but does not contrast against other aggregate siblings like get_visibility_overview.

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