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

Annotations already declare it is a non-read, non-destructive, non-idempotent write, so the bar is lower. The description still adds real value beyond them: union semantics with the existing list, no metrics refresh, and no credit cost ('Free'). It stops short of mentioning the 500-keyword cap or any permissions, but the added context is substantive.

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 with zero filler, and the core capability is front-loaded before the routing advice. Every clause earns its place, including the cost note.

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 two-parameter write tool with full schema coverage, no output schema, and informative annotations, the description covers purpose, alternative, side effects (no metrics refresh, union merge) and cost. Nothing needed to call it correctly is 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?

With 100% schema description coverage, both parameters are documented in the schema and the baseline of 3 applies. The description only implies the source of the 'keywords' values (research or rankings) and the union merge behavior, adding little syntax or format detail 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 verb and resource ('Bulk-saves keywords ... into the customer's own keyword list'), plus scope ('in one call', 'bulk'). It also names the sibling it is contrasted with (add_my_keywords), so the agent can distinguish it without opening either 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?

Explicitly routes the agent: 'Prefer add_my_keywords for a few keywords; use this when saving many at once.' Both the alternative and the selecting condition are stated, leaving nothing to inference.

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