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

Annotations already declare readOnly, idempotent, and non-destructive, but the description adds substantial context beyond them: the per-post billing model, the extra profile lookup billed only on the first page, the 404/privacy behavior for protected accounts, and the empty-list behavior for non-Premium accounts. This is exactly the kind of operational detail an agent needs before invoking a billed, paginated read.

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 front-loaded with purpose and scope, then moves through edge cases, billing, and pagination in a logical order. It is somewhat dense — the billing sentence is long — but each clause carries operational information an agent would otherwise lack.

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?

There is no output schema, yet the description explains that the return is a list of featured posts, how pagination works via meta.nextCursor, what happens on missing/protected accounts, and how billing accrues. For a read-only, paginated, metered tool, nothing material is missing.

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?

With 100% schema description coverage the baseline is 3, but the description adds meaning beyond the schema for the cursor: later pages 'carry the account in the cursor and do not' incur the lookup charge, and the agent must call again with cursor set to meta.nextCursor. It also clarifies that the first page resolves the {user} argument at extra cost, which the schema alone does not convey.

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 states a specific verb and resource — 'Get the posts an X account highlights' — and immediately explains the scope: 'Returns the profile's Highlights tab: posts the account chose to feature.' This differentiates it from siblings like get_x_user_posts and get_x_posts without the agent needing to inspect those 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?

It gives clear contextual guidance: only Premium accounts can highlight so the list is empty otherwise, a 404 occurs for nonexistent or protected accounts, and pagination is driven by meta.nextCursor. It does not explicitly name alternative tools such as get_x_user_posts for a general timeline, but the 'featured' distinction makes the right choice obvious.

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