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

Annotations already flag readOnlyHint=false and openWorldHint=true, but the description adds genuinely useful context: despite sounding like a lookup, the returned ideas are persisted to the website's keyword list. It also names the response fields. It stops short of describing auth needs, rate limits, result counts, or whether existing keywords are overwritten.

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?

Two tight sentences with no filler, and the core purpose is front-loaded. The second sentence about persistence is the most decision-relevant fact and is placed well, though the phrase 'in the plan' is slightly ambiguous about which plan.

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 no output schema, the description usefully summarizes the returned fields, and it discloses the write side-effect. However, for a 3-parameter, 0%-coverage tool it leaves the two ID parameters unexplained and says nothing about result volume, cost, or how repeated calls interact with the existing keyword list.

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 must carry parameter meaning. It only implies the mapping for 'query' via 'seed phrase'; siteId and projectId are undocumented in both the schema and the description, leaving two required identifiers with no semantics at all.

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 ('look up keyword ideas for a seed phrase') plus the fields returned (volume, difficulty, plan membership), so the agent knows exactly what the tool produces. It does not distinguish itself from near-siblings such as list_article_keywords, add_article_keywords, or import_article_keywords, which is the main clarity gap.

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?

No explicit when-to-use or when-not-to-use guidance and no alternatives named. The use case is only inferable from the verb phrase 'look up keyword ideas for a seed phrase'; nothing tells the agent whether to prefer this over list_article_keywords or add_article_keywords.

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