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

Annotations already declare readOnlyHint/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely non-derivable behavior: results are ordered 'best first' and, importantly, 'a missing number is not reported yet, never zero' – a data-semantics rule an agent could otherwise misread as a real zero. Scope is also constrained to the artist's own posts. Pagination/window mechanics are left to 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?

The primary output is front-loaded in the first sentence, which is good, but it is a dense, comma-piled run-on, and the second 'what_works' sentence is a chain of clauses that is hard to parse. Meaningful content, but not tight or scannable.

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?

There is no output schema, so the description has to carry the return-shape burden and largely does: it enumerates the per-post metrics, the window totals, the follower counts, and the what_works breakdown. Combined with 100% schema coverage on inputs, an agent has enough to call and interpret the result, with only ordering/pagination details 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 100%, so days, limit, and artist are fully documented in structured form and this is the baseline case. The description only loosely reinforces the artist scoping ('from their own posts only') without adding range, default, 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 resource (the posts that went out) and the exact payload: reach, likes, comments, shares, saves, views, window totals, per-account followers, plus a per-platform what_works analysis. An agent knows what it returns. It never names or contrasts a sibling such as get_stats or promo_this_week, so the boundary is left to inference rather than stated.

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?

The description gives no when-to-use framing, no prerequisites, and no explicit alternative to choose instead. The only routing hint ('from their own posts only', label vs artist connection) lives in the schema's artist parameter, not in the description. An agent must infer that this is the historical-results counterpart to promo_this_week.

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