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

The annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuine value by stating the membership precondition and the derived fields returned (owner, role, server-derived actor). It adds nothing about failure modes—e.g. what happens when you are not a member—which would have earned a higher score.

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 front-loaded sentence with no filler; the access precondition and the returned fields are both stated compactly.

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?

An output schema exists, so return values need not be spelled out, and annotations cover safety. The membership constraint is disclosed. The one real omission is any guidance on space_id format/derivation, which matters given 0% schema description coverage.

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%, so the description must carry the parameter explanation, and it does not: space_id is never mentioned. The schema's key constraint (the '^[so]_[0-9a-f]{32}$' pattern signalling that the id may be prefixed 's_' or 'o_') is entirely unexplained, leaving the agent to infer which identifier form to supply.

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 gives a specific verb ('Read') and resource ('a private Space'), and enumerates the payload conceptually (paying owner, your role, caller actor). It implicitly contrasts with list-style siblings by implying a single-space fetch, but it never names private_space_list or private_space_get_actor as the alternatives.

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?

'a private Space you currently belong to' establishes a real prerequisite: the caller must be a member. There is no explicit exclusion or named alternative, so it stops short of the 5 bar, but the usage context is clear enough for an agent to pick this over list/search tools.

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