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

readOnlyHint=true already establishes this is a safe read, so the description only needs to add context. It usefully discloses the shape of the return – full post samples selected by engagement – which matters here because no output schema exists. It does not mention volume, limits, or auth requirements.

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?

Two sentences with no filler; the payload description comes first and the usage trigger second. Appropriately sized for a no-parameter read tool.

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 no parameters, no output schema, and a read-only annotation, the description carries most of the informational load and does so adequately by explaining both the return content and when to call it. Minor gaps remain around result volume and recency of the sampled posts.

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?

The tool takes zero parameters, so there is nothing to document and the baseline for this dimension is 4.

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 specifies the resource (the user's Substack writing voice/patterns) and the payload composition – best-liked posts in full plus the posts that drew the most likes and comments. The verb is implicit rather than stated outright, but an agent can distinguish this from siblings like get_substack_posts or get_substack_post_stats.

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 concrete trigger conditions: call before drafting a Substack post or Note, or when the user asks what to write next. No alternative or exclusion is named (e.g., when a generic style read is not wanted), so it stops short of the top score.

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