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

With no annotations provided, the description carries the full behavioral burden. It discloses the 1-credit cost, that empty results and failures are never charged, and the free 24h cache-hit behavior with fresh-by-default semantics. It does not mention auth, rate limits, or error formats, but for a simple read endpoint this is solidly transparent.

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 description is two sentences with no filler. It front-loads the action and returned data, then packs cost, failure policy, and cache behavior into the second sentence. Every clause earns its place.

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?

For a simple 2-parameter read tool with no output schema, the description compensates by listing the expected return fields and operational details like credits and caching. It is sufficient for an agent to call correctly, though it could go further by naming sibling alternatives for disambiguation.

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%, and the schema already thoroughly documents both url and cache semantics. The description repeats the cache behavior but adds no new parameter-level meaning beyond what the schema provides, so the baseline of 3 is appropriate.

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?

Description uses a specific verb and resource: 'Get an Instagram post, Reel or carousel' and lists concrete return fields (caption, likes, comments, views, media URLs, author, per-slide children). This clearly distinguishes it from sibling endpoints like instagram_basic_profile, instagram_channel_posts, or instagram_embed.

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?

The description implies when to use this tool by scoping it to posts, Reels, and carousels, and it gives useful cache usage guidance. However, it never explicitly names alternatives or states when to prefer a sibling tool such as instagram_comments or instagram_channel_posts, so usage context is implied rather than explicitly routed.

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