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

Annotations already declare the full safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false, openWorldHint=false), so the description's burden is lighter. It adds that the target list must already exist and that only saved properties can be added, but says nothing about duplicate handling, size limits, or what happens on partial failure.

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 zero filler, appropriately sized for a two-parameter tool. It is efficient, though it borders on under-specification rather than optimal density.

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 simple two-parameter mutation with full schema coverage and clear annotations, the description is minimally sufficient. It omits anything about the result of the operation or edge-case behavior (duplicates, invalid list_id), which leaves real gaps for a mutation tool.

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%, and the schema already explains that list_id is a UUID from a Spur list/search tool and that property_ids come from spur_list_saved_properties or spur_save_properties. The description contributes no additional parameter meaning beyond the schema, so the baseline of 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?

The description names a specific verb and resource ("add saved properties to an existing property list"), and the word "existing" implicitly distinguishes it from spur_create_property_list. It does not explicitly name or contrast with any sibling, 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?

There is no guidance on when to choose this tool over alternatives such as spur_save_properties or spur_create_property_list, nor any prerequisite or exclusion statements. Usage is only inferable from the word "existing."

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