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

Goes well beyond the annotations: dedup semantics (same person kept once), no per-list size limit, a 5000-chat batch cap, duplicate vs invalid handling, and the crucial "Sends nothing" assurance that clarifies what destructiveHint=true does not mean here. Missing only authorization requirements and whether partial success is possible.

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 dense sentences, front-loaded with the write marker and the action, with constraints folded into parentheses. Some nesting reduces scanability slightly, but no sentence is wasted.

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 3-parameter mutation with no output schema, the description covers batch limits, dedupe, invalid-input handling, and the no-message-send behavior, which is close to what an agent needs. It stops short of permission prerequisites and the shape of the duplicate/invalid counts returned.

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 0%, so the description carries the load: it explains that tg_chat_ids are chat IDs from any of the merchant's accounts with a 5000-item cap, and that tg_list_id or tg_list_uuid identifies the target list. It does not state which of the two list identifiers is required or how conflicts are resolved, which the schema also leaves ambiguous.

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 ("Adds chats ... to a saved list") plus the list identifiers, and the "[write]" prefix makes the operation class unmistakable against read-only siblings like list_tg_list_members. An agent can pick this over remove_tg_list_members or the email/sms/voip/wp equivalents from the description alone.

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?

Implies the usage context (adding chats that belong to the merchant's accounts to an existing saved list) and the 5000-per-call ceiling, but never explicitly names alternatives or when-not to use it — e.g., no pointer to create_tg_list for new lists or remove_tg_list_members for removal. Guidance is present but inferential.

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