signin_logs

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

With no annotations provided, the description carries the full burden and excels. It discloses read-only permissions (AuditLog.Read.All or Reports Reader), retention limits (30 days), clamping behavior, client-side filtering, page-walking mechanics, and the meaning of capped=true. It even clarifies that low match counts with capped=true indicate a budget limit, not absence of data. This is a model of transparency.

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 well-structured, front-loading the core purpose, then providing necessary nuance about filtering and paging, then permissions, then a clean parameter list. Every sentence contributes to correct usage; there is no filler or redundancy. It is long but appropriately so for a tool with complex client-side behavior.

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?

Given the complexity (client-side filtering, pagination, permission requirements, retention window, edge cases) and the absence of an output schema, the description is remarkably complete. It covers all scenarios an agent needs to invoke the tool correctly and interpret results, including the capped flag and empty results. Nothing critical 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?

Schema description coverage is 0%, but the description compensates thoroughly. It explains each parameter in detail: user's userPrincipalName, hours clamped to [1,720], result options with default 'failure', top clamped to [1,500], and max_pages with default. It also explains the functional meaning of result (client-side filter) and the cap semantics, providing far more than 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 explicitly states the tool returns 'one user's recent sign-in events' and frames it as 'the most direct answer to why can't this person log in'. It identifies the AADSTS annotation as a key value-add, distinguishing it from sibling tools like signin_failure_stats that likely provide aggregated statistics. The purpose is specific and immediately actionable.

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 explicit usage context: it is positioned as the go-to for individual login troubleshooting, and it explains important behavioral caveats like client-side filtering that require adjusting expectations. It implies when not to use it (e.g., for stats, use signin_failure_stats) and details what happens when the page budget is exhausted (capped=true). Alternatives are not explicitly named but clearly indicated by context.

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