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

Annotations already declare the write/idempotent/non-destructive profile, lowering the bar. The description adds a genuinely useful signal that this is a full replacement (not a patch) and that ownership is required, but it never warns that unspecified fields fall back to empty defaults, which is the key behavioral consequence of a replace.

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 tight sentences, front-loaded with the action and the ownership constraint, then the critical version requirement. Nothing is wasted.

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 an 8-parameter mutation with nested objects, the schema carries the full burden of field documentation and there is no output schema to explain, so the short description is nearly sufficient. It misses only the replace-defaults behavior, which would materially affect how an agent populates optional fields.

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 100%, so all 8 parameters are documented in the schema. 'Pass the version you last read' largely restates expected_version's own schema text, adding little beyond it; baseline 3 applies.

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?

Specific verb (replace) plus resource (space) and scope (you own), and the word 'replace' usefully clarifies the semantics versus the name's 'update'. It does not explicitly name siblings like create_space or join_space to steer selection, so it stops short of a 5.

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?

Usage is only implied (you'd use it to change an existing space you own). The one real guideline given is 'Pass the version you last read', a concurrency instruction rather than a when-to-use or when-not-to-use statement, and no alternatives are named.

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