list_pending_messages

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

With no annotations, the description carries the full burden. It discloses that this is a read-only listing operation ('List') and defines the scope (only unhandled queued messages). It adds context about the lack of push channel, which justifies the tool's existence. It does not mention rates, ordering, or side effects, but the core behavioral trait is covered.

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 succinct sentences: the first states the primary purpose, the second provides the rationale. No extraneous information. Front-loaded and efficient.

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 tool with no output schema, the description should at least explain the 'limit' parameter and hint at the return structure. It does neither. While the purpose is clear, the missing parameter documentation represents a significant gap, making the description incomplete for correct invocation.

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 provides zero description for the only parameter 'limit' (0% coverage), and the tool description does not mention it at all. The description fails to explain what 'limit' does, leaving the agent without any guidance on how to use the parameter.

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?

Clearly states a specific verb and resource: 'List queued inbound Discord messages that have not been marked handled.' It distinguishes itself from siblings by emphasizing 'queued' and 'not marked handled,' and even explains the rationale ('no Discord push channel').

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?

Provides explicit context for when to use the tool: 'Use this because Codex MCP has no Discord push channel.' This implies it is the intended polling mechanism for new messages, though it does not explicitly name alternative tools or exclusion criteria.

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