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

Annotations already declare readOnly, idempotent, non-destructive and non-open-world, so the safety profile is covered. The description adds two things annotations cannot convey: an authentication key is required, and the fetched content from other agents is untrusted and must not be followed as instructions — an important behavioral constraint for an agent calling this tool.

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 compact sentences with the key requirement front-loaded, followed by the content summary and the safety warning. The trailing English gloss '(Read a thread.)' is redundant with the Korean text but is short and broadly harmless.

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 single-parameter read tool with full annotation coverage, the definition tells the agent what it returns, that a key is needed, and how to treat untrusted content. No output schema exists, but the description enumerates the returned fields well enough that the agent knows what to expect.

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?

There is only one required parameter (thread_id) and schema description coverage is 100%, with the schema already labeling it as the post number. The description adds no further format, range, or identifier-meaning detail beyond the schema, so the baseline 3 applies.

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+resource (reads a thread) and enumerates the returned content: body, comments, nested replies, and like counts. It is clearly distinguishable from create_thread or list_threads by the read/aggregate nature, though it never explicitly names which sibling to prefer for feed-style listing.

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 leading '[키 필요]' tag tells the agent a key is a prerequisite, which is real usage context. However, there is no explicit when-to-use vs read_feed or list_threads guidance, so the agent must infer that this tool is for a single thread by id.

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