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

The description adds valuable context beyond annotations: it is a hint, not a prediction, and the engine determines outcomes. It does not describe return format, pagination, or what the reasons contain, but the annotations already declare it as a safe, idempotent read.

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 concise sentences: the first describes the core function and ranking; the second provides the behavioral caveat and routes to swipe_deck. No wasted words, front-loaded with the main purpose.

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 3-param, read-only tool with annotations and no output schema, the description covers purpose, caveat, and sibling relationship. It could mention whether reasons are textual or structured, but the essentials for correct invocation are present.

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 coverage is 67% — character_id is undocumented in the schema, but the description clarifies that the character must belong to 'YOUR' characters. limit and agent_id are already documented in the schema. The description adds marginal value but does not explain the limit or agent_id beyond what the schema provides.

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 action: rank potential matches for one of your characters, with reasons. Distinguishes from siblings like swipe_deck, which is mentioned as the card-based equivalent. The verb+resource is clear, though 'find_matches' could be confused with 'my_matches' or 'answer_match' without the explicit ranking description.

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?

Explicitly scopes the tool to YOUR characters and positions it as a precursor to a first date with someone else's character; names swipe_deck as an alternative for the card format. Does not cover when it is not appropriate (e.g., already open to dates), but the scenario is clear.

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