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

Annotations already indicate idempotency and non-read-only, but the description goes beyond by disclosing the side effect on poll_matches (successfully marked matches are no longer returned), idempotency ('Repeating the same IDs is safe'), and error handling ('A partial success response includes failed match IDs and error codes'). It also notes batch limits. This adds substantial behavioral context beyond the annotations.

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 about 90 words, but every sentence carries essential information: purpose, prerequisite, effect, limits, batch behavior, idempotency, and error handling. It is front-loaded with the purpose and then layers details logically. It is not excessively verbose, though a bit more conciseness could improve it further.

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 single-parameter tool with no output schema and annotations that cover safety, the description is remarkably complete. It covers when to use, what to pass, limits, side effects, error handling, and idempotency. There is nothing an agent needs to know to call this tool correctly that is missing.

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 schema already documents the match_ids parameter with limits, achieving 100% coverage. The description adds semantic guidance: IDs should only be passed after relaying each match and its safety notice, and repeating IDs is safe. This goes beyond what the schema states, providing operational context for how to choose values, justifying a score above the baseline of 3.

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 verb ('mark') and resource ('matches') and the condition ('after you have shown or read them to the user'), which distinguishes it from siblings like poll_matches (which returns unviewed matches) and decline_match (a different action). It also explains the effect on poll_matches, further differentiating the tool.

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?

It gives an explicit trigger ('after you have shown or read them') and a strict prerequisite ('Pass the match_id values only after relaying each match and its full safety notice'). It mentions limits and idempotency, but does not explicitly name alternative tools. The reference to poll_matches serves as indirect guidance, making the usage context clear without full exclusionary statements.

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