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

Annotations already declare readOnlyHint=true, so the description goes beyond by disclosing the source field values ('env', 'set_active_space', 'default'), the fallback to the caller's Personal Space, and the no-API-round-trip behavior when unbound. This is rich behavioral context.

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?

Three sentences with no fluff. The first sentence states the purpose, the second lists return fields and source values, and the third covers the no-round-trip edge case. Every sentence earns its place.

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 parameterless getter with no output schema, the description fully documents the return shape, source values, and the unbound fallback behavior. It is complete for an AI agent to invoke and interpret results correctly.

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 tool has zero parameters, so the schema already covers 100% of parameter meaning. The description does not need to compensate, and the baseline of 4 applies. It does explain the return object, which is relevant to the tool's semantics.

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 clearly states the tool reports the MCP server's current active Space binding, with a specific verb+resource and a detailed return object. This distinguishes it from siblings like set_active_space and list_spaces.

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?

Clear context as a read-only getter for the active space, with source semantics explained. No explicit when-not or alternative mentioned, but the obvious counterpart is set_active_space, so the usage is implied.

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