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

Goes well beyond the annotations (readOnlyHint=false, idempotentHint=false, destructiveHint=false) by disclosing non-obvious behaviors: duplicates are silently ignored, saving queues an async lookup of volume/difficulty/coverage, and new entries show 'researching' in list_my_keywords for minutes. This is exactly the async-state context an agent needs and cannot get from the schema.

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 tight sentences that are front-loaded with the core purpose, then layered with duplicate handling, async status, and activation timing. Every sentence contributes information an agent would otherwise have to discover empirically.

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 mutation tool with annotations carrying the safety profile and no output schema, the description covers the essential unknowns: what is mutated, dedup behavior, the asynchronous side effect, where to observe it (list_my_keywords), and how to trigger downstream use (generate_plan). 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?

Schema description coverage is 100%, so the schema already documents both parameters (site and keywords, including the 100-item cap and 200-char limit). The description adds no syntax or format guidance for either parameter, so the baseline 3 is appropriate.

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 ('Adds keywords to the customer's own list') and even anchors it to the UI location (Settings > Keywords), which disambiguates it from the many other keyword tools in the sibling list. An agent can immediately tell this adds to a personal keyword list rather than saving a research set or excluding keywords.

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 operational context: it's free, the planner picks entries up on its next refill, and the agent can call generate_plan to force the update sooner. It does not explicitly contrast with save_keywords or state when not to use it, so it falls short of the 5-level 'when/when-not/alternatives' bar.

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