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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the read-only behavior is covered. The description adds meaningful behavioral context by clarifying that aggregation spans ALL child user links, that it returns campaign-level totals and per-user breakdowns, and that it requires a parent short code. No contradiction with 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 appropriately sized and front-loaded: first sentence states the core behavior, second gives the usage context, third enumerates useful return fields since there is no output schema, and fourth clarifies the sibling boundary. Each sentence earns its place with no redundancy.

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 read-only aggregation tool with no output schema, the description is complete: it names the full set of return fields, explains the required input and its provenance, gives the typical use case, and routes the agent to the correct alternative when needed. Nothing critical for correct invocation 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?

Input schema coverage is 100%, so the baseline is 3. The description adds extra value by telling the agent where to obtain parentShortCode (from nevent_list_short_urls where isParent=true) and reinforcing that it is the campaign parent code. This goes beyond the schema's field description, though days and topN semantics are left to 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 opens with a specific verb-resource pair: 'Get aggregated click metrics across a parent short URL and all its per-user variants.' It clearly distinguishes from sibling nevent_get_short_url_metrics by emphasizing aggregation across child links, so an agent can tell them apart immediately.

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 explicitly states when to use the tool: after a marketing campaign with per-user tracking links, and even names the creating tool (nevent_create_bulk_user_short_urls). It also directs the agent to the alternative, nevent_get_short_url_metrics(id), when a per-link breakdown is needed, which fully addresses when-versus-alternatives.

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