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

With no annotations, the description carries the full burden and does disclose two useful behavioral facts: cost (1 credit) and required auth (Bearer api_key). However, it omits return format and pagination/resumption behavior despite the cursor and chunk_size parameters, leaving notable gaps for a data-fetch tool.

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?

Purpose is front-loaded in the first sentence and the description is short. There is some waste: 'Platform=instagram resource=tagged' largely restates the name, and there is a stray double period, but the credit and auth notes earn their 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 read/fetch tool with no output schema and no annotations, the description covers purpose, cost, and auth, which is adequate. It stops short of describing the return shape or pagination behavior, which an agent would need to page results 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 description coverage is 100%, so cursor, user_id, and chunk_size are already documented in the schema. The description adds no parameter meaning beyond what the schema provides, so the baseline 3 applies.

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 gives a specific verb (Fetch) and resource (public posts where a user id was tagged), making it distinguishable from instagram_posts (posts authored by a user). It does not name a sibling explicitly, but the 'tagged' qualifier clearly scopes the operation.

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?

It supplies a use-case hint ('brand mentions and collaboration discovery') but gives no explicit when-to-use/when-not guidance or named alternatives (e.g., instagram_posts for authored content). Usage is implied rather than directed.

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