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

Annotations already declare the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description is free to add the parts annotations cannot: the data is derived from this org's own history (not global benchmarks) and normalized to its timezone. With no output schema, describing the return shape as a weekday × hour grid is genuinely valuable, though limits like history depth are left to the 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?

Two sentences, zero waste. The output shape is front-loaded and the practical takeaway (which slots to feed into `scheduledFor`) follows immediately.

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 read-only analytics tool with three fully-documented optional params and no output schema, the description covers both the return shape and data provenance, which is enough to call it correctly. The one real gap is that it does not help the agent choose between it and the near-identical `suggest_publish_times` sibling.

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 description coverage is 100%, so all three parameters (days, accountId, workspaceId) are already fully documented with defaults and fallback behavior. The description adds nothing beyond the schema here, so the baseline of 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?

The description names a specific artifact — a 'weekday × hour engagement grid' built from the organization's own history in its timezone — so an agent knows exactly what it gets back. It is clear on its own, but it never distinguishes itself from the very similar sibling `suggest_publish_times`, leaving the agent to guess which to call.

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 only implied: 'the top slots are good `scheduledFor` candidates' signals the downstream scheduling intent, which is helpful. However, there is no explicit when-to-use vs. when-not, and no mention of the obvious alternative (`suggest_publish_times`) or prerequisites, so the agent must infer routing.

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