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

Annotations already declare the tool as read-only, idempotent, and non-destructive. The description adds valuable context beyond those: 'Keyless' (no authentication required), 'live' (real-time data), and 'non-completed' (filtering behavior). It does not discuss rate limits or pagination, but with strong annotation coverage this is acceptable.

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 entire description is one concise sentence that front-loads the action and resource, then provides the key return details and behavioral notes. Zero filler.

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 list tool with one optional parameter and no output schema, the description is largely complete: it names the data returned, the live nature, and the filtering. It lacks explicit differentiation from siblings (get_fissures) but still gives sufficient context for selection and invocation.

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 single optional parameter (platform) is fully documented in the schema with a clear description and default, so the description doesn't need to add more. The description's mention of 'keyless' pertains to authentication rather than parameter semantics; it does not enhance understanding of the platform field beyond the schema.

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 uses a specific verb ('List') and identifies the exact resource ('active faction Invasions'), and names the returned fields (node, factions, completion). It clearly distinguishes from sibling get_fissures by stating it's about Invasions specifically, not other world state.

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 implies usage for checking live, non-completed invasions and notes it's keyless, but it does not explicitly state when to use this over alternatives like get_fissures or world_state, nor does it provide any exclusions.

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