List available OpenRouter models

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

Annotations already establish readOnlyHint, idempotentHint, and non-destructive behavior. The description adds genuinely useful behavioral context beyond the annotations: the catalog is 'live', results may change over time, and the tool supports substring search, a free-only filter, and cursor pagination. No contradiction.

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?

Three sentences with no filler: the first gives the primary purpose, the second summarizes key capabilities compactly, and the third explains why the tool should be used now before consulting. The most decision-relevant detail is front-loaded.

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?

The description is sufficient for a read-only listing tool with no required parameters. It explains the dynamic nature of the resource, mentions the main filtering and pagination controls, and orients the agent toward its downstream use with consult. No output schema exists, but the tool's return shape is inferable from the catalog-listing purpose.

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 only 40%, so the description carries extra weight. It compensates by describing the behaviors that map to query (substring search), free_only, and cursor, and the sort enum is self-documenting via its option names. Only limit gets no added semantic context, but its schema min/max constraints partially cover that.

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 states a specific verb and resource ('Browse the live OpenRouter model catalog') with a clear purpose ('pick an exact panel for consult'). It differentiates itself from the sibling tools by being catalog-specific: consult performs a consultation, get_status and get_debug_logs concern system state, not model listing.

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?

The description gives clear context: this is the tool to use for resolving model ids before a consult, and the warning that 'Model ids change over time' implies using it instead of hardcoding. It does not explicitly name an alternative or provide when-not-to-use guidance, but the context is unambiguous given the sibling set.

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