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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely new operational context: cost ('1 credit per call') and pagination behavior ('Returns an end_cursor for more'), both of which affect how an agent should budget and loop calls.

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 purpose, then intent, then cost and pagination — dense and mostly well-ordered. The trailing 'Inputs:' sentence duplicates the schema verbatim and earns little, a minor but real waste.

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?

Covers purpose, intended use, cost, pagination, and the shape of results, and an output schema exists so return values needn't be detailed. Adequate for a 2-parameter, low-complexity search tool; only the redundant parameter recap and lack of exclusions keep it from 5.

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 schema already documents both parameters. The 'Inputs: keyword (required), end_cursor (optional)' line merely restates the schema and adds no syntax, format, or usage nuance beyond it, matching the baseline for fully-documented params.

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 and resource ('Search Instagram by keyword') and enumerates the three result types (users, hashtags, places). It also differentiates itself from siblings by naming instagram_location and the action=posts flow, so an agent can route without opening other schemas.

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 concrete triggering intents: find a username, or resolve a place's location_id for instagram_location (action=posts). That is clear when-to-use guidance tied to a downstream tool. It does not state when-not-to-use (e.g. vs instagram_profile lookup by known handle), so it falls short of the top bar.

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