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

With no annotations, the description carries the full burden and does well: it discloses the auth requirement (skanfirmy API key), the null-name edge case for natural persons, and the exact shape of returned status fields. It stops short of stating read-only semantics explicitly or any rate/pagination behavior, but the return contract is unusually well disclosed.

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?

Dense but efficient: the core return contract is front-loaded in the first clause, then edge cases and derived fields follow. Only minor tightening would be possible without losing the useful detail.

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?

There is no output schema, so the description must explain return values and it does so thoroughly (status_vat raw literal, derived vat_active and status_vat_code with enum-like values, null-name case). Auth is also covered, leaving little an agent needs that isn't stated.

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 there is only one optional parameter, so the schema already documents api_key fully. The description reinforces the API-key requirement but adds no syntax or fallback detail beyond what the schema provides, making the baseline 3 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 and resource ('Return the list of NIPs you monitor') and immediately scopes what each entry contains. An agent can distinguish it from siblings like observe_nip, unobserve_nip, and changes_since without opening any schema.

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: the tool reads the monitored-NIP set, while observe_nip/unobserve_nip mutate it. The description never explicitly says when to reach for this versus changes_since or sprawdz_nip, and offers no exclusions or prerequisites beyond the API key.

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