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

Annotations already declare read-only, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuinely new behavioral content beyond that: it enumerates what identity facets are returned, explains defaultContext auto-resolution, and notes that version/toolCount expose stale client discovery caches.

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 compact sentences, front-loaded with the primary capability. Dense but nearly every clause conveys a distinct returned field; minor cost is that terms like 'credential narrowing' and 'ambiguousAt' are used without unpacking.

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?

With no output schema, the description carries the burden of describing return values, and it does enumerate the main ones (principal, narrowing, project count, serverVersion, toolCount, defaultContext, ambiguousAt). Some fields are named without explaining their shape or values, leaving a small gap.

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 tool takes zero parameters, so the baseline is 4. The description spends its space describing outputs instead, which is appropriate and adds no confusion about inputs.

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 verb and resource: 'Read the authenticated principal, credential narrowing, accessible project count, serverVersion and toolCount.' An agent can tell this is an identity/context introspection tool. However, it does not distinguish it from the sibling get_profile, which plausibly covers similar ground.

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?

No explicit when-to-use statement or alternative named. Usage is only implied through phrases like 'matching calls without explicit IDs' and 'evidence of stale client discovery caches,' which hint at diagnostics without telling the agent when to pick this over get_profile.

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