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

With no annotations, the description carries the transparency burden. It discloses that only matching callers may perform the action, that the space owner and Admin/SuperAdmin always bypass (no lockout), and how 'space_role' matching works (>=). This is substantial beyond the schema, though it does not mention reversibility or duplicate handling.

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 well-structured: it starts with a parenthetical role qualifier, defines the operation, enumerates parameter values in compact bullet-like lines, explains behavioral implications, and ends with a concrete example. Every sentence adds value without redundancy.

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 tool's moderate complexity (4 required parameters, no output schema), the description covers all essential aspects: purpose, parameter semantics, behavior, and an example. It is self-contained and leaves little ambiguity for an agent invoking it. The only minor gap is the explicit format of 'slug', which is easily inferred from 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?

Schema coverage is 0% and only lists parameter names and unconstrained strings, so the description is essential. It explains valid values for 'action', 'subject_type', and provides an example for 'subject_value'. However, 'slug' is only implicitly defined as the space identifier, and no explicit format is given, so the description does not fully compensate for the schema 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 ('Restrict') with a clear resource ('a space action') and the object ('to a subject'). It distinguishes from sibling tools that list or remove access rules, and the 'Space manager' prefix adds context. The example further clarifies the purpose.

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 clearly implies this tool is for adding access rules and provides context on when rules take effect ('When rules exist for an action, only matching callers may perform it'). It does not explicitly mention alternatives (e.g., use list_access_rules to view rules), but the behavior and example give sufficient guidance for correct use.

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