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

Beyond the sparse annotations, the description discloses real behavioral traits: creators receive a push notification, re-assigning an already-assigned post updates rather than duplicates, and the update is partial (only provided fields are refreshed). This gives the agent critical side-effect and mutation semantics that annotations do not convey.

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?

Three dense sentences with no filler: the core action is first, followed by prerequisites and then important update/notification semantics. Every sentence contributes information an agent needs before calling the 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?

The description covers prerequisites, side effects, and the update path, which is sufficient for a mutation tool with a fully documented schema. It could be slightly more complete by explicitly routing update-only intent to update_assignment or describing the success response, but these are minor gaps.

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?

Input schema already documents all six parameters (100% coverage), so the baseline is 3. The description adds genuine value by clarifying the folder parameter's behavior ('applied as-is to every creator; per-creator folder auto-routing is not applied') and by connecting post_id/models to lookup tools, pushing it above baseline.

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 identifies the action ('Assign a viral post to one or more creators') and the resource/scope, and even calls out the Production workflow. It does not, however, explicitly contrast itself with the sibling update_assignment or list_assignments, so it misses the explicit sibling differentiation that would earn a 5.

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 states a concrete prerequisite ('post must already exist in the library') and points to relevant lookup tools (list_viral_posts / analyze_post_url). It describes the notification side effect and the re-assignment update path, but it does not say when NOT to use this tool or mention update_assignment as the alternative for updating an assignment.

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