Keyword detail in one market

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

Annotations already declare readOnly, idempotent, closed-world, non-destructive, so the safety profile is covered. The description adds genuine value by disclosing the return payload groups (current cell, daily history, ranking apps including title/subtitle match flags), which matters because there is no output schema. It does not mention truncation behavior or how history points relate to the requested ranges, but the core behavioral surface is described.

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?

A single sentence that front-loads the scope ('Everything about one keyword in one market') then lists the three returned payload groups. No filler, no restatement of the title, and every clause maps to something the tool actually returns.

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 correctly shoulders the burden of describing return content and does so at a useful granularity for a read-only detail endpoint. Minor gaps remain: it does not clarify how many history series are returned (rank vs. popularity separately) or how the response behaves when historyPoints or topApps are 0.

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%, with market format, defaults, and ranges all documented in the schema, so the baseline of 3 applies. The description reinforces the market scoping and that history is day-granular, but adds nothing about topApps or historyPoints semantics beyond what the schema already states.

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 resource and scope (one keyword in one market) and enumerates the exact payload: current cell metrics, daily rank/estimate history, and ranking apps with their fields. That enumeration cleanly separates it from get_project_board (which lists keywords) and search_store (which finds apps), without needing to name them.

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?

Usage is only implied: an agent can infer this is the drill-down for a keyword surfaced elsewhere, reinforced by the schema noting keywordId comes from get_project_board. There is no explicit when-to-use statement, no when-not-to-use, and no guidance on when to prefer this over the board or app-level tools.

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