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

The description is consistent with the existing readOnlyHint: true annotation and adds a modest behavioral detail—that the tool returns aggregated counts rather than the full memory contents. However, since the annotation already establishes the safe read-only profile, the description's additional behavioral disclosure beyond that is thin, mirroring the get_calls calibration case.

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 tightly packed sentences with zero wasted words: the first states the function, the second prescribes when to use it. Every word earns its place, front-loaded with the key verb and resource.

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 tool with no parameters, an existing output schema (documenting the return), and a readOnlyHint annotation, the description covers purpose, output nature (counts per chapter), and call timing. Given the tool's low complexity, nothing essential is missing—only hypothetical color about ordering or edge cases could add anything.

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?

With zero parameters and 100% (vacuously) covered schema, there is literally nothing for the description to add about arguments or inputs. Per the rubric's baseline for a 0-parameter tool, a 4 is appropriate—the description correctly implies this is a fire-and-forget aggregate call requiring no user input.

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?

"Get memory count per chapter" pairs a specific verb (Get) with a specific resource (memory count per chapter), clarifying that this is an aggregate, grouped operation rather than a raw listing. This meaningfully differentiates it from siblings like countMemories, listMemories, and searchMemory, while decoding what the vague title 'Chapter Overview' actually does.

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 as FIRST STEP in new conversations or reviews" provides an explicit trigger for when to invoke the tool, effectively positioning it as the entry point for fresh context. However, it stops short of naming alternatives or exclusions (e.g., when to choose countMemories or searchMemory instead), so it doesn't fully reach the top of the scale.

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