download_file

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

Annotations already indicate readOnlyHint=false and destructiveHint=false, but the description adds valuable behavioral context: 'Saves locally' (side effect on filesystem), 'returns the path' (output behavior), and 'Max 20MB (Telegram Bot API limit)' (constraint). This goes beyond annotations without contradicting them.

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 sentences, front-loaded with the primary action and immediate outcome. Every clause earns its place: download mechanism, result, usage context, and size limit. No fluff or repetition.

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 simple two-parameter tool with full schema coverage and no output schema, the description is complete. It covers usage timing, size constraint, and return value (path), giving the agent enough context to invoke the tool correctly without needing return format details.

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 100%, with both file_id and dest_dir clearly documented. The description adds no additional parameter-level detail beyond what the schema already provides, so a baseline of 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?

Description explicitly states 'Download a file from Telegram by file_id' with a specific verb (download), resource (file), and mechanism (file_id). It also adds outcome ('Saves locally and returns the path'), making it unambiguous and distinct from siblings like get_file which likely only retrieves metadata.

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?

The description provides clear context on when to use: 'Use after receiving a message with a photo, video, document, voice, etc.' It does not explicitly mention alternatives or exclusions (e.g., 'for metadata only, use get_file'), so it falls short of a 5 but is well above no guidance.

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