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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real value by stating what is returned (guide, pricing model, memoryBlock) and implies a follow-up action — persisting the memoryBlock into CLAUDE.md/AGENTS.md/.cursorrules. It doesn't describe the size or format of the guide, so not 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?

A single front-loaded sentence that leads with the WHEN TO CALL trigger and then lists the return contents. Every clause carries information; nothing is redundant.

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 input parameters and no output schema, the description carries the burden of explaining what comes back — and it does, naming all three return components. It could go slightly further by noting that the guide is static reference material versus live tool data, but it's sufficient for correct invocation.

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 tool takes zero parameters, so the baseline is 4 per the rubric. There is nothing for the description to disambiguate, and it doesn't waste space on phantom parameters.

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 uses a specific verb (returns) and names the concrete artifacts returned: the full tool guide, the free-vs-paid model, and a memoryBlock snippet. This distinguishes it from sibling tools like discover_tools or route_task. It falls short of 5 only because it doesn't explicitly contrast itself with those siblings by name.

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?

The 'WHEN TO CALL: once per project, or when unsure...' phrasing gives clear triggering conditions, including a frequency cap. It doesn't state when NOT to call it or name a specific alternative for the 'I already know what I need' case, which keeps it below 5.

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