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

Annotations already establish a safe, idempotent, open-world read, so the bar is lower. The description adds useful context beyond annotations: a membership restriction, an auth/key requirement, and a bounded return ('the last 20 messages'), but the truncated final clause leaves the returned threads' behavior unclear.

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 text is short, but it is not concise in a useful sense: it is an incomplete fragment ending in an ellipsis. The front-loaded 'Members only' is efficient, yet the unfinished sentence leaves core content unstated rather than merely trimmed.

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 read tool with no output schema and no schema descriptions, so the description must explain both inputs and what context is returned. It partially lists the payload but leaves parameters undefined and the final return component truncated, so an agent cannot reliably call it or predict what it receives.

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 0% for two parameters, so the description must carry the burden. 'Needs key or sign-in' loosely maps to the key parameter as an auth credential, but the required 'space' parameter is never explained, leaving the primary input ambiguous.

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 enumerates what the space context contains (mission, plan, members, shared repos, recent messages, linked threads), which hints at the resource involved, but it never states a verb and trails off mid-sentence ('with their...'). The relationship to siblings like space_read or space_thread_read is left for the agent to guess.

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 does not say when to call this versus space_read, space_thread_read, or space_unread. 'Members only' and 'Needs key or sign-in' are access conditions, not usage guidance or alternative selection criteria.

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