GitHub MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states 'Update an existing issue,' which implies a mutation operation, but fails to disclose critical traits: whether authentication is required, what permissions are needed, if changes are reversible, rate limits, or what the output contains. For a mutation tool with zero annotation coverage, this is a significant gap in transparency.

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 extremely concise—just one sentence—with no wasted words. It's front-loaded with the core action ('Update an existing issue'), making it easy to parse. Every sentence earns its place, though it could benefit from additional context.

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?

Given the complexity (a mutation tool with 8 parameters), no annotations, and the presence of an output schema (which reduces the need to explain return values), the description is minimally complete. It states the purpose but lacks usage guidelines, behavioral details, and parameter insights beyond the schema. It's adequate for basic identification but insufficient for informed tool invocation in a rich sibling context.

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 schema description coverage is 100%, with detailed parameter descriptions in the input schema (e.g., 'New title', 'New state (open, closed)'). The tool description adds no parameter information beyond what the schema provides. According to the rules, when schema coverage is high (>80%), the baseline score is 3, as the schema does the heavy lifting.

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 'Update an existing issue' clearly states the verb ('Update') and resource ('an existing issue'), which is adequate for basic understanding. However, it doesn't differentiate this tool from similar sibling tools like 'update_pull_request' or 'update_gist'—it merely restates the tool name without specifying what aspects of an issue can be updated or the scope of changes.

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 no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., needing repository access), exclusions (e.g., when not to update), or comparisons to sibling tools like 'create_issue' or 'get_issue'. This leaves the agent without context for tool selection in a server with many issue-related tools.

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