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

Annotations cover the safety profile (readOnly=false, destructive=false, idempotent=true, openWorld=true), and the description adds real substance on top: the return is a link valid 90 days, identical events+title deterministically yield the same link, and unknown ids surface as 'missing' rather than failing. That determinism and error-handling detail is exactly the behavioral context an agent needs before calling a creator tool.

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?

Front-loaded with the core action and output URL, then trigger phrases, then behavioral facts. Dense and mostly waste-free, though the first sentence carries several clauses at once and the quoting of Russian trigger phrases adds bulk.

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, the description needn't explain return shape, and it still covers the essentials an agent would otherwise guess: what gets created, link lifetime, idempotency semantics, and how invalid input is reported. Nothing material is left open for a 2-parameter creation tool.

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 description coverage is 100% — both parameters are already documented with bounds (2–10 items, order preserved, Russian title, no links/emoji). The description only restates that ids come from previous results and adds the unknown-id outcome, which is return behavior rather than parameter meaning, so it sits at the baseline.

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 (save), a constrained resource (2–10 events from previous results), and the concrete artifact produced (a shareable page at spontanno.space/s/{code}). This is unmistakably distinct from sibling readers like search_events or get_event.

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?

Gives explicit triggering contexts — «скинь списком», «сохрани», «отправлю друзьям», and after planning an evening or weekend — so the agent knows when to reach for it. It stops short of naming when NOT to use it or pointing at an alternative, but the when-to-use signal is strong.

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