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

Annotations already establish read-only, non-destructive, open-world. The description goes beyond them with real operational detail: a max 365-day window, a 1 hour cache with 'refresh is true' to rebuild (noting it is slower), and the explicit data-coverage caveat that non-Breakreach posts are included, which concretizes the openWorldHint. No authentication or rate-limit behavior is mentioned.

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?

Three compact sentences, front-loaded with purpose and scope before the usage tip and the caching caveat. Every sentence carries information, though the metric enumeration and the cache sentence could be tightened slightly.

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 helpfully outlines the return shape (per-post metrics plus totals per platform) and covers the cost/latency tradeoff of refresh, so an agent can call it correctly. Minor gaps remain: no mention of pagination behavior past the limit cap or how results are ordered when sorting by a non-date field.

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 baseline is 3 and the schema already documents days (1-365), limit (max 200), sortBy enum, and refresh semantics. The description mostly restates those bounds and adds only the sortBy+limit combination example, which is a marginal gain over what the schema provides.

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+resource (per-post performance metrics) and enumerates the returned measures (views, likes, comments, shares, engagement rate, per-platform totals). The scope sentence 'Covers ALL posts on the connected Instagram, Facebook, Threads, X, YouTube and Bluesky accounts, including posts not made with Breakreach' distinguishes it from single-post siblings like get_post_insights and get_post_metrics without needing to open any schema.

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 actionable usage context, including a concrete pattern: 'Use sortBy + limit for top posts, e.g. sortBy=views, limit=10.' It also frames the refresh flag as the escape hatch from the 1 hour cache. It stops short of naming when NOT to use it or naming sibling alternatives (get_analytics, get_account_trends), so it is clear but not exhaustive.

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