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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description contributes what annotations cannot: the shape and contents of the response (grade, benchmark comparisons, working/needs-attention split, trends, priority action). It does not address the scope of 'recent' (how many campaigns, what time window) or caching/rate behavior, which keeps it from a 5.

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 tight sentences with zero filler: purpose first, output contents second, routing guidance last. The most decision-relevant information (it's a fast overview, not deep analysis) is front-loaded.

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 output schema, the description's enumeration of return contents does the necessary work, and the sibling routing is unambiguous. The only meaningful gap is the undefined scope of 'recent campaigns' (count or time window) and whether the portfolio spans all campaigns or a filtered subset.

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?

Only one optional parameter, cost_per_email, and schema description coverage is 100% with its own dollar-denominated explanation. The description adds no parameter detail at all, so the schema carries the full burden and 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: portfolio-level health check across recent campaigns, then enumerates exactly what the returned dashboard contains (grade, metric status vs benchmarks, what's working vs needs attention, trends, top priority action). It also names the sibling analyze_latest_campaigns as the differentiator, so an agent can distinguish the two without opening a schema.

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?

Explicitly splits the decision space: 'Use this for a fast 10-second overview; use analyze_latest_campaigns for deep analysis.' Both the when and the named alternative are stated outright, leaving nothing for the agent to infer.

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