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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safe/read-only nature is covered. The description adds a behavioral requirement to 'Preserve its chat_id + message_id pair,' which is useful context beyond annotations. However, it does not disclose response characteristics, error behavior, or any rate limits, so it adds modest value but does not fully cover the behavioral burden.

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 verbose and largely repeats the schema's property descriptions verbatim. While the opening line is concise, the subsequent Chat ID and Message ID sections are redundant given the 100% schema coverage, making the description feel bloated rather than earn its length. The structure is organized with labels, but the content is not streamlined.

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 read-only listing tool, the description covers parameters thoroughly and annotations confirm safety, but it does not describe the expected return shape or any additional context like pagination of reactions. Without an output schema, a brief note on what 'detailed reactions' includes would improve completeness. The description is adequate for basic invocation but not fully rich.

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 description duplicates the parameter guidance already present in the input schema (e.g., 'Never pass: person name' for chat_id). It reiterates the importance of pairing chat_id and message_id, but this is also found in the schema's message_id description. The description adds no new meaning beyond the schema, 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?

The description opens with 'List detailed reactions on one exact message,' which clearly specifies the verb (list), the resource (reactions), and the scope (one exact message). This differentiates it from siblings like message_add_reaction and social_list_comment_reactions by focusing on reading reactions for a single chat message, not modifying them or targeting comments/posts.

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 implies the tool is for reading reactions on a message but does not explicitly state when to use it over alternatives such as social_list_comment_reactions or when not to use it. It focuses on parameter acquisition rather than providing usage context relative to sibling tools, so the guidance is only implied, not explicit.

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