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

The description discloses many behavioral traits beyond annotations: parse_mode=rich cannot be combined with files, file attachments make the message a caption, channel posts with reply_to_id automatically post in the linked discussion group, and return/error formats are specified. It also notes that local paths work only in stdio mode. No contradiction with the annotations (openWorldHint, destructiveHint).

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?

The description is relatively long but every sentence adds value—no fluff or repetition. It front-loads the core purpose, then covers parameters, edge cases, return values, and alternatives in a logical order. The documentation link is a useful appendix without cluttering the main text.

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?

Given the tool's complexity (5 params, 2 required, enums, output schema), the description is remarkably complete. It explains return value structure (message_id, status, error handling), critical constraints (rich cannot combine with files), platform-specific behavior (stdio local paths), and documents all parameter semantics. No gaps remain.

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%, but the description adds substantial context: chat_id formats (numeric, username, 'me'), files support data URIs and local path restrictions, parse_mode enum semantics with rich message dialect detection, and reply_to_id behavior for forums and channels. This goes well beyond the schema definitions.

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?

The description clearly states the tool's function: "Send text and optional file attachments to a Telegram chat." It identifies the specific verb (send), resource (Telegram chat), and scope (text and optional file attachments), and it distinguishes from siblings by naming alternatives like edit_message and send_message_to_phone.

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?

Explicit guidance is provided: "Use send_message to create new messages; use edit_message to modify existing ones. Use send_message_to_phone when targeting a phone number instead of a chat_id." This directly tells the agent when to choose this tool versus alternatives, exceeding simple context.

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