Current ratings

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the useful behavioral fact that records are lifetime (not windowed) and covers four named time controls, but says nothing about auth requirements, rate limits, or behavior when no username is supplied.

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?

One sentence, front-loaded with the payload ('current and best rating'), with the enumerated time controls serving as a compact scope statement. 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 simple one-parameter read tool with no output schema, the description effectively documents the return shape by listing the data categories. The only shortfall is the undefined behavior of the optional username argument.

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 coverage is 100% and the single username parameter is fully documented there, so the schema does the heavy lifting. The description adds no information about the parameter — notably it never explains what happens when the optional username is omitted, which is the one semantic gap.

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 names a specific resource (ratings) and enumerates exactly what is returned: current and best rating plus lifetime win/loss/draw per time control. That content profile implicitly separates it from siblings like recent_games and month_summary, though no sibling is named explicitly.

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 only implied by the data scope — an agent can infer this is the tool for a rating/record snapshot, but there is no statement of when to prefer it over get_profile or month_summary, and no exclusions or prerequisites.

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