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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false and destructiveHint=false, so the safety profile is covered. The description adds nothing beyond repeating schema property names: it does not warn that retries create duplicate issues (non-idempotent), does not mention required permissions, and does not say what happens when labels or assignees do not exist.

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?

A single short sentence with no filler and the core action front-loaded. It is lean, though its brevity comes at the cost of the missing detail noted elsewhere rather than through efficient prioritization.

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?

This is a non-idempotent write tool with no output schema and mostly undocumented parameters, yet the description never covers authentication, required fields, duplicate-risk on retry, or what the response contains (issue number/URL). For a mutation tool in a large sibling set, that leaves the agent under-equipped.

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 only 20% (only 'repo' is documented, with the owner/name format). The description merely lists 'title, body, labels and assignees' without adding format details — e.g. whether assignees are GitHub usernames, whether labels must already exist, or title length constraints — so it does not compensate for the coverage gap.

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 ('Open an issue') and enumerates the settable fields, which clearly separates it from gh_issue_update and gh_issues. It stops short of explicitly naming sibling alternatives, so a 4 rather than 5.

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?

There is no guidance on when to use this tool versus gh_issue_update (to modify an existing issue) or gh_issues (to read them), and no prerequisites such as repo access or authentication. The agent must infer usage entirely from the name.

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