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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. Without an output schema, the description's enumeration of what the insights contain (growth trajectory, engagement health, projected growth) does real work. It says nothing about data freshness, whether projected growth is modeled, or what happens for private/small accounts.

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 sentences, front-loaded with the capability and followed by trigger conditions. No filler and nothing that could be cut without losing information.

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 spends its words describing return contents, and a single-parameter read-only tool needs little else. The remaining gap is ambiguity versus look-alike siblings (get_growth_summary, get_account_stats) rather than missing invocation detail.

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?

Only one parameter, and the schema fully documents it ("Instagram username (without @)") at 100% coverage, so the baseline is 3. The description adds no semantics about the identifier, such as whether it must be a monitored account or what happens on an unknown handle.

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?

The description uses a specific verb and resource ("Get audience and growth insights for an Instagram account") and enumerates the content: follower growth trajectory, engagement health, projected growth. It is clear, but it does not distinguish itself from siblings like get_growth_summary or get_account_stats that appear to overlap substantially.

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?

"Use this when someone asks about their audience, who follows them, growth trends, or account health" gives concrete trigger phrasing an agent can match on. It stops short of exclusions or alternatives, and notably does not resolve the apparent overlap with get_growth_summary and get_account_stats.

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