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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds real behavioral content beyond that: the tool has two distinct response modes (section index with group counts vs. groups plus base points) and that service_date selects the release 'in force', which is a temporal-resolution rule not visible in annotations. It does not describe pagination or limits, which is the only shortfall.

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 sentences, zero filler, with the core mode-switching rule front-loaded and the routing advice trailing. Dense but every clause carries information an agent needs.

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 an output schema present, return values need not be explained, and annotations cover safety; the description supplies the mode logic and next-step routing, so an agent can call it correctly. The one uncovered edge is partial argument combinations (catalog without section, or an out-of-range section) and whether group counts are paginated, which leaves a small gap.

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%, so per-parameter meaning is already documented ('omit with section for the index', 'Section number from the index', 'Day of care, YYYY-MM-DD; default today in Poland'). The description contributes the cross-parameter interaction — that omitting both yields the index and supplying both yields the section detail — which the schema only hints at.

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 and resource (browse the JGP catalog) plus the exact resolution rule: index of sections with group counts when catalog+section are omitted, that section's groups and base points when both are given. It also names the sibling tools for the adjacent tasks (search_codes for finding a group, get_jgp_group for opening one), so it is clearly distinguishable from 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?

Explicitly encodes the two usage modes and the parameter combination that selects each, then routes the agent onward: 'Find a group by words with search_codes; open one with get_jgp_group.' That is when-to-use plus named alternatives, not mere implication.

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