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

Annotations already cover read-only, idempotent, open-world and non-destructive traits, but the description adds real behavioral context the annotations cannot: the shared size budget across photos, client image-block dropping behavior, and that each photo returns a link. It stops short of describing failure modes when a message_id is not a photo.

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 purpose and the sibling comparison before any detail; every sentence carries information, though the closing instruction about including links in the reply is slightly incidental.

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 compensates by telling the agent what comes back (photos plus a link each) and how to use it, and the two required parameters are covered. Nothing needed to invoke it correctly is missing.

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 baseline is 3, but the description adds a genuine constraint beyond the schema: the message_ids must correspond to messages whose message_type is 'photo', which the schema's 'photo messages' phrasing only implies.

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 ('Look at several photos from one chat') plus the batching scope ('in a single call'), which cleanly separates it from the singular telegram_get_photo sibling.

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 says 'Prefer this over calling telegram_get_photo repeatedly' and gives the reason (shared size budget, six cost about one; clients that drop separate image blocks keep these), so both the when and the why are present.

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