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

Goes well beyond the annotations by disclosing that each call is a priced search, that it takes several seconds, that it reads a public page through a gateway, and the exact error signal ERR_IG_PAGE_UNAVAILABLE with a recovery action. Annotations cover safety only, so this cost/latency/error context is genuinely additive.

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?

Front-loaded with the '[read]' tag and the core action, then the return shape, then the failure mode and cost. Dense but every clause carries new information; the heavy parenthetical nesting makes it slightly harder to scan than it needs to be.

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?

Despite having no output schema, the description enumerates the returned fields (heading, description, keywords, reels, users) and caps. Combined with error semantics and cost/latency, an agent has everything needed to call it and interpret the result.

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 coverage is 0%, so the description must carry the load, and it does: `count` is explained as the reel cap with a hard ceiling of 28 (and default 10 visible only in schema), and `keyword` is framed as a topic phrase with the caveat that unknown phrases fail. The default for `count` is not restated, keeping it just under a 5.

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 concrete verb+resource ('Look a topic up on Instagram') plus the exact upstream path (/popular/{topic}/ via the Instagram Trends gateway). An agent can distinguish it from the many sibling trend searchers (search_rd_trends, search_yt_trends, search_tt_videos, list_twitter_trends) without opening the 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?

Implied usage is clear (search an Instagram topic) and it usefully says what to do on failure ('try a shorter, more common keyword'), but it never routes the agent explicitly against the sibling trend tools that exist for YouTube, TikTok, Reddit and Twitter. No 'when not to use' or alternative-naming guidance is given.

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