Aws Scale Readiness

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

Annotations already declare read-only, open-world, idempotent, non-destructive behavior, so the safety profile is covered. The description adds genuinely new context beyond them: the data window (7 days of CloudWatch), the exact upstream API surface ('Describe and GetMetricData only'), which signals required IAM permissions, and the evaluation order ('Findings first'). It stops short of stating result size or failure behavior, but the added value is real.

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 dense sentences with the resource and data window front-loaded and the enumerated checks following. Every clause carries information, though the telegraphic, fragment-like style ('Findings first: is scale-in safe...') requires a second read and could be tightened.

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 full schema coverage, a complete annotation set, and an output schema covering return structure, the description only needs to convey what the check assesses and where the data comes from — both are present. The only gap is guidance relative to overlapping diagnostic siblings, which is a minor omission for a low-parameter read-only tool.

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?

Schema description coverage is 100% for both parameters, with region defaulting to AWS_REGION and replication_group_id documented inline, and an output schema exists. The description contributes nothing about the parameters themselves, so the baseline of 3 applies — the schema does all the work here.

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 states a specific assessment goal — headroom for resharding or a node-type change — and enumerates the checks it performs (scale-in safety via projected memory per surviving shard, scale-out advice, node-type-change risks). That is far more specific than the name alone and implicitly separates it from pure metric tools. It does not name a sibling (e.g. aws_capacity_forecast or aws_shard_balance) to draw the boundary explicitly, which keeps it below a 5.

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?

Usage is implied by the framing: this is the tool to call before resharding or changing node type. However, there is no explicit 'use this when' sentence, no stated exclusions, and no pointer to the related tools that cover overlapping questions such as capacity forecasting or shard balance, so the agent must infer the boundary.

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