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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds real value beyond that: per-call pricing (1 credit), pagination via end_cursor, and the shape of nearby results (name, category, coordinates, post count). It does not discuss rate limits or auth requirements, which are the remaining behavioral gaps.

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 action-bulleted layout is front-loaded and easy to scan, and each action states its purpose, inputs, and cost. It loses a point for redundancy: 'Pricing: 1 credit per call' and 'Needs a location_id' are each repeated verbatim across both actions.

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?

An output schema exists, so return values need not be exhaustively explained, yet the description still summarizes what nearby returns and flags the pagination cursor for posts. Both actions, their required vs optional parameters, the location_id prerequisite, and cost are all covered, leaving nothing an agent needs to invoke the tool correctly.

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 100%, so the baseline is 3. The description goes slightly beyond the flat schema by mapping parameters to actions ('Inputs: location_id (required), tab (optional), end_cursor (optional)') and by clarifying tab semantics as 'top posts (tab=ranked)' vs 'most recent (tab=recent)', which the schema only labels as 'recent' or 'ranked'.

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 opens with a specific verb+resource ('Instagram locations: posts tagged at a place, and nearby places') and breaks the tool into two clearly delineated actions, posts and nearby. It distinguishes itself from siblings by explicitly pointing to instagram_search (action=search) as the source of location_id, so an agent can route between the two without opening 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?

Each action carries its own usage context: posts offers tab=ranked for top posts vs tab=recent for recency, and the prerequisite location_id is named along with where to obtain it (instagram_search action=search). What's missing is explicit when-not guidance, e.g. when to prefer instagram_post over this tool for a single post.

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