Start Telegram login

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

Annotations already declare readOnlyHint=false and openWorldHint=true, so the description is not carrying the safety profile alone. It nonetheless adds real behavioral context: the tool sends a code to the user's Telegram app, honors the TELEGRAM_PHONE env fallback, and enforces a security rule about never echoing the code. Return format is not covered, but with annotations present this is solid.

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 trigger condition and effect, then the required input format, then the mandatory follow-up and security constraint. Every sentence carries actionable information with no padding.

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 two-parameter, no-output-schema tool, the description covers the precondition, the side effect, input formatting with env fallback, the next step, and a security constraint. Nothing needed to call 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; the description earns a bump by adding the TELEGRAM_PHONE environment fallback for phone, which is not visible in the schema. The force parameter's 'only when the user asks' guidance duplicates the schema description rather than extending it.

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 ('Begin authorization') with the triggering condition ('when no session exists') and the concrete effect ('Sends the login code to the user's Telegram app'). It clearly differentiates itself from the sibling telegram_login_code, which is named as the follow-up step.

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 an explicit precondition ('when no session exists') and routes the agent to the correct next tool ('call telegram_login_code'), plus the phone-vs-env behavior. It does not explicitly say what to do if a session already exists (e.g. use telegram_status), so it stops just short of full when/when-not guidance.

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