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

Annotations already state that this is a safe read-only operation, and the description adds meaningful context beyond them: token-based visibility and the fact that 'comments' is only a count. The guidance to read the thread via get_comments explains an important behavioral nuance that would otherwise cause misuse.

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 two sentences, front-loaded with the primary action and then the important comments caveat. Every sentence adds useful information with no repetition or filler.

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 one-parameter read-only retrieval tool with no output schema, it covers the visibility condition, the returned issue fields, and the key comments distinction. An agent has enough information to invoke this tool correctly and know when to follow up with get_comments.

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?

The single parameter is fully documented in the schema, so baseline credit applies. The description repeats the example key format but does not add syntax or constraints beyond what the schema already provides.

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 states a specific verb and resource: 'Get one issue by key'. The singular key and mention of visibility distinguish it from search/list siblings such as find_issues and search_issues without requiring schema inspection.

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?

It clearly says when to use this tool: retrieving one issue by key when visible to the token. It also names the alternative get_comments and gives an explicit condition for using it whenever the comments count is nonzero.

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