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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds that `query` performs fuzzy normalization of city names ('Питер', 'Екб', «в Нижнем»), which is useful behavioral context, but omits anything about result ordering or pagination behavior for the list mode.

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, both densely packed with no filler, and the coverage-checking purpose is front-loaded ahead of the usage condition. The sentences are long, but every clause carries routing or behavioral information.

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?

An output schema exists so return values need no explanation, and the description is complete enough to select and invoke the tool in either mode. The only gap is that it doesn't tell the agent how the two modes' outputs differ in practice or when to prefer the list mode over a targeted query.

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%, so both parameters are already documented in the schema, including the 'any form' behavior of `query`. The description only restates this, adding the overview dimensions returned (counts, free events, categories), which is return-value information rather than parameter meaning.

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 ('Check which Russian cities СПОНТАННО covers and how many events each has') and covers both operating modes: the no-argument list mode and the `query` resolution mode. It is clearly distinguishable from siblings like search_events and get_event, which operate on events rather than city coverage.

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 names the conditions under which to use it: 'when unsure whether a city is covered' or 'when the user asks what is happening in a city in general.' Clear positive guidance, but it never names an alternative sibling (e.g., search_events for specific event lookups) nor states when not to use it.

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