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

Annotations already declare readOnly, non-destructive, and closed-world behavior. The description adds meaningful context beyond annotations: authentication requirement ('Needs the read scope'), cost ('Free'), and the meaning of the multiplier sort. Return format is covered by the output schema.

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 tightly packed sentences with no wasted words. Scope and sorting are front-loaded, followed by cost, expansion alternative, and auth requirement.

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?

With an output schema, full parameter descriptions, and annotations covering safety, the description supplies the remaining key context: auth scope, cost, sorting semantics, and pagination alternative. A minor gap is that it mentions topic faceting without a corresponding topic parameter, and it does not state its relationship to posts_list.

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 parameters are already documented. The description adds value by defining multiplier as 'views against the account's own median,' which the schema enum alone does not explain. It also clarifies the platform/topic faceting context.

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 clearly states it reads every post held for a person or account, with sorting and platform/topic facets. It distinguishes the expansion path via identity_expand, but does not explicitly differentiate from siblings like posts_list that may also return posts.

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 useful context: the tool is free, requires the read scope, and points to identity_expand for pulling more. It does not explicitly say when to choose this over posts_list or other identity siblings, so the guidance is helpful but not complete.

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