Sync the local index

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

Annotations already declare readOnlyHint, idempotentHint=false, and destructiveHint=false; the description usefully explains why non-idempotency exists (incremental chunked backfill up to max_messages, default 2000) and what comes back ('Returns what changed per room'). It does not address the side effect of the `full` flag discarding the local copy, which is a noticeable omission for a tool whose local state is its core resource.

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?

Four short sentences, each carrying distinct load: purpose, backfill/retry mechanics, return value, and read scope. The core purpose is front-loaded with no filler.

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 competently covers the return shape ('what changed per room') and the retry loop, and annotations cover safety. Slightly more detail on the response or on the `full` re-index behavior would close the remaining gap for an incremental-sync 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 coverage is 100%, so the baseline is 3, but the description adds meaning beyond the schema: it reveals the default chunk size (2000) and the per-room chunking behavior of max_messages, plus the room-default semantics. These behavioral defaults are not documented in the schema properties.

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 ('Fetch new, edited and deleted messages into the local index of decrypted messages') with clear scope ('for one room or for all rooms'). None of the sibling names (get_message, search, list_rooms, etc.) describe an indexing/sync operation, so the agent can distinguish this tool immediately.

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 actionable operational guidance: 'if `note` says history is incomplete, call again,' which tells the agent how to handle a partial backfill rather than guessing. It lacks explicit when-not-to-use or direct sibling comparisons, but the read-only scope note signals it is not a search/retrieval alternative.

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