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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds genuinely useful context beyond that: that the data is real-time (not cached/historical), the exact endpoint, and the return envelope { stats: [...] }, which tells the agent what to expect without an 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?

Three short sentences: purpose first, endpoint second, return shape third. Every sentence carries information and there is no 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 single-parameter read tool with no output schema, the description supplies the return envelope and the stat categories, which is sufficient to call it correctly. It stops short of describing individual stat fields or freshness semantics (e.g. polling behavior), which would make it 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?

Only one parameter exists and schema coverage is 100%, with the schema already explaining that 'app' accepts a name (my-production-app) or an id (app-…). The description adds nothing parameter-level, so the baseline 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?

States a specific verb (get real-time stats) and a precise resource (per-container CPU/memory/swap usage) for an app, and even names the underlying endpoint. It is clearly distinguishable from scalingo_list_containers in substance, but it never explicitly contrasts itself with that sibling.

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 'real-time' framing implies this is for live resource monitoring rather than inventory listing, but the description gives no explicit when-to-use, when-not-to-use, or alternative routing. Usage is left to inference.

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