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

Annotations already cover the read-only and open-world profile, and the description adds genuinely useful behavior: the 700-keyword ceiling, workspace-defaulted location/language, and a precise error contract (single-element list with api_error/task_error, dfs_timeout, dfs_unreachable) that the agent must check before parsing. It stops short of mentioning cost, rate limits, or latency for what is an external paid API.

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?

Four short lines, each carrying distinct information: outputs and cap first, then defaults, then the error contract, then the workspace caveat. Nothing is redundant and the most important constraint is front-loaded.

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 an output schema present, return values need not be described, and the remaining gaps an agent would hit — batch limits, defaults, error shapes, workspace optionality — are all covered. Only the location/language encoding and any cost/latency expectation are left implicit.

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 0%, so the description is the only source of parameter meaning — and it covers all four: keywords as a list with a 700-item cap, location/language inheriting workspace defaults, and workspace being optional when only one workspace exists. The location/language value format is offloaded to a sibling reference rather than spelled out, which keeps it from a 5.

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?

The description names the exact metrics returned (volume, CPC, difficulty, search intent, 12-month trend) plus the input shape (keyword list, max 700), which is a clear verb+resource statement. It does not explicitly differentiate itself from dfs_keyword_volume or dfs_keyword_trends beyond referencing the former's output format.

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?

There is no statement of when to choose this over dfs_keyword_volume, dfs_keyword_trends, or dfs_keyword_suggestions, all of which live in the same family. The only implicit guidance is the 700-keyword cap and the note that location/language default from the workspace, neither of which tells the agent when this tool is the right pick.

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