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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so safety is covered. The description adds real context beyond them: the result set is capped at the 30 most recent posts, it is scoped to the connected Instagram account, and it is fetched live from Instagram rather than cached — all of which affect expectations about freshness and completeness.

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?

One sentence, front-loaded with the verb and the resource, with the rule-related purpose and the live-read caveat following. The phrasing 'for post_id on a comment DM rule' is slightly compressed but nothing is wasted.

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 one-parameter read with no output schema, the description covers what is returned (30 most recent posts), whose account it comes from, and how fresh it is. The only mild gap is the absence of any note about what happens when the account has fewer than 30 posts or no Instagram connection.

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 a single parameter at 100% schema coverage, the schema already explains workspace_id and even points to list_workspaces. The description adds nothing about the parameter itself (the mention of post_id refers to the returned values, not the input), 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?

States a specific verb and resource (lists the connected Instagram account's 30 most recent posts) and ties the result to the post_id needed by a comment DM rule. It is clear on its own, though it never explicitly contrasts itself with nearby siblings such as list_comment_dm_rules or get_post_details.

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?

Usage is implied rather than stated: the phrase 'for post_id on a comment DM rule' suggests you call this when configuring a comment DM rule and need a post to target. There is no explicit when-not guidance and no named alternative for fetching post IDs or post details.

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