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

Annotations cover the safety profile (destructiveHint=true, idempotentHint=true, openWorldHint=true), and the description adds genuinely new behavior: the other person is notified, only standard Telegram emoji are accepted, and omitting emoji removes the reaction. The notification side effect is exactly the kind of consequence an agent needs before acting.

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 sentences, all information-bearing, with the scope constraint front-loaded before the caveats. Slightly dense, but nothing is redundant with the schema or annotations.

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?

For a mutation tool with no output schema, the description covers scope, side effects, parameter edge cases, and a user-confirmation safeguard. An agent has everything needed to call it correctly and safely.

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 baseline is 3. The description adds a constraint not in the schema — only standard reaction emoji are accepted — and reinforces the omit-to-remove semantics for `emoji`, going modestly beyond the structured fields.

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 (react) and resource (a message in the bot's OWN DM), and immediately scopes it against the main archive and other chat types. An agent can distinguish it from telegram_set_reaction or telegram_bot_dm_reply without opening a 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?

Gives clear context: only chats returned by telegram_bot_direct_messages, explicitly not groups and not 1:1 business chats, plus a 'confirm with the user first' instruction. It never names the sibling tool to use for the excluded chat types (e.g. telegram_set_reaction), so the routing guidance is one step short of fully explicit.

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