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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds the framing that these pages are 'usually the cheapest wins' but does not disclose additional behavioral details such as return format or pagination; this is acceptable given the annotations, though the description adds little beyond the tool's concept.

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?

The description is only two sentences and both are immediately understandable, with the core concept front-loaded. The second sentence is a useful strategic heuristic rather than filler.

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 list tool, the schema plus annotations cover parameter meaning and safety, leaving the description to explain what the tool surfaces—which it does. However, it does not mention output shape or period-comparison details beyond the schema, and there is no sibling routing, so the description is adequate but not fully complete.

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?

The input schema provides descriptions for all three parameters (site, days, limit), so schema coverage is 100%. The description does not add parameter-level meaning beyond what the schema already conveys, apart from framing the output as 'fading' pages, which is implied by the tool name and title. The baseline of 3 is appropriate.

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 resource ('pages that used to bring clicks and are fading') and the intended follow-up action ('refresh instead of writing something new'), so the purpose is understandable. However, it relies on a noun-phrase style and the title rather than an explicit verb like 'lists' or 'identifies', and it does not differentiate from sibling tools such as find_opportunities.

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?

There is no explicit guidance on when to use content_decay versus alternatives like find_opportunities or indexing_gaps. The only advice is strategic ('cheapest wins: refresh instead of writing something new'), which tells the agent what to do with the results, not when this tool should be selected. No exclusions or alternative tool names are provided.

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