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

Annotations already declare readOnlyHint and openWorldHint, yet the description adds substantial context: pricing model ($0.002 USDC per successful call via x402 on Base/Solana/Arc), that failed calls are not charged, and the ~20-post cap. Pricing and failure-charging semantics are behavior an agent cannot get from the structured fields.

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?

Three tight clauses: what it fetches, the scope limit, and the price. Front-loaded with the resource and what's returned, with no filler sentences.

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?

Output schema exists, so return values needn't be re-explained; the description still covers scope, cost, and result granularity. For a single-param read tool this is fully complete.

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% and the single 'channel' param is fully documented with format rules. The description adds only indirect context ('public channels') without new syntax details, so baseline 3 is appropriate.

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 resource (public Telegram channel via the t.me/s preview page) and enumerates exactly what is returned (title, description, counts, ~20 posts). An agent can distinguish it from the telegram_homepage and telegram_keyword_search siblings by the concrete output footprint.

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 states the negative condition: 'Only public channels that show a preview; private chats and groups are not returned.' That is a clear scope exclusion. It does not name the sibling alternatives, but the exclusion is strong enough for reliable selection.

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