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

Annotations already declare this is a non-read-only, non-destructive, non-open-world write; the description adds the key behavioral fact that previously saved listings are refreshed rather than duplicated, which annotations cannot express. It does not cover failure behavior or what is returned, but the essential mutation semantic is disclosed.

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 sentences, no filler, with the core action and its input source front-loaded before the dedupe caveat. Every clause carries information the agent needs.

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 mutation tool with no output schema, the description covers the input source, the upsert behavior, and the optional list target, which is enough to call it correctly. Return values and handling of invalid or oversized batches (maxItems 50) are left implicit.

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%, including the note that listings must be copied unchanged from spur_search_properties, so the description largely echoes structured fields. The mention of the optional property list adds a little context but does not go beyond what the schema's list_id description already says.

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?

States a specific verb and resource ('Save live listings into the user's Spur properties') plus the optional list scoping, which separates it from spur_add_properties_to_list and spur_list_saved_properties. The sentence 'Already-saved listings are refreshed, not duplicated' further pins down the semantic of the operation.

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?

Gives concrete input provenance: pass listing objects from spur_search_properties structuredContent.cards[].listing, which tells the agent exactly where to source arguments. It does not explicitly state when to use this instead of spur_add_properties_to_list, so a small gap remains on the alternatives side.

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