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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds meaningful context by specifying that results are aggregates and listing which dimensions are summarized, which helps an agent reason about the payload shape despite no output 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?

Front-loaded with the purpose, followed immediately by usage context, then the parameter note. Three compact sentences with no wasted language.

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?

No output schema exists, yet the description covers the return content by naming the aggregate metrics, so an agent knows what it gets back. Combined with the read-only annotation, nothing needed to call it correctly is missing.

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?

Zero parameters, so baseline is 4. The description's 'No parameters required' explicitly confirms what the empty schema already implies, leaving no ambiguity.

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 ('Returns') and resource ('aggregate platform statistics'), then enumerates the concrete metrics (campaign counts, category distribution, donation totals, funding gaps). This clearly separates it from the record-level siblings like get_campaign and search_campaigns.

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?

'Use this before search_campaigns' gives explicit sequencing guidance against a named sibling, a strong signal. It stops short of stating when NOT to use it or ruling out the other siblings (get_campaign, get_campaign_donations), but the intended context is clear.

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