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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is fully covered structurally. The description adds useful content-level context (plan, limit consumption, entitlements) but says nothing about authentication requirements, whether it fails when unauthenticated, or freshness of the usage counters.

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 well-formed sentence with no filler, front-loaded on the return content. It is appropriately sized, though it could be marginally tighter by ranking the most important returned field first.

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 output schema, the description carries the burden of describing return values, and it does so by enumerating the three content groups an agent will receive. For a zero-parameter, read-only tool this is close to sufficient; only the authentication precondition is left implicit.

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?

Zero parameters, so there is nothing for the schema to document and the baseline of 4 applies. The description correctly implies the identity is taken from the session rather than from 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?

States a specific verb ('Vrátí') and resource (the logged-in user's tarif), plus the concrete data returned: daily limit usage and features available in the plan. It is unmistakably distinct from siblings like detail_bodu or smlouvy_obce, though it does not explicitly contrast itself with any of them.

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?

No when-to-use guidance, no prerequisites, and no alternatives named. The purpose is self-evident enough that an agent can infer 'call this when you need the signed-in user's account state', but that is inference, not stated guidance.

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