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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-structured context: that the returned tenantTimezone governs every yyyy-MM-dd date filter and that relative dates must be computed in that zone, not UTC — an important behavioral rule an agent would otherwise get wrong.

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?

Two sentences with no filler: the return contents come first, then the operational consequence (timezone-correct date math). Every clause carries information an agent needs.

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?

There is no output schema, yet the description names the fields returned (tenant ID, user ID, role, tenantTimezone) and explains how to use the timezone value. For a zero-parameter, read-only tool this is sufficient to invoke and interpret the result correctly.

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 no parameters, so the baseline is 4. The description correctly says nothing about inputs and instead spends its words on the return payload, which is the right allocation for a zero-argument call.

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 ("Show") plus a precise resource ("current authentication info") and enumerates the returned fields (tenant ID, user ID, role, tenantTimezone). No sibling tool does anything comparable, so an agent can identify this as the identity/timezone lookup without opening the schema.

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 gives clear situational guidance: use it to obtain the tenant time zone and to resolve "today"/"yesterday" relative to it rather than UTC. It does not name alternative tools or explicit exclusions, but with zero parameters and no functional siblings there is little to disambiguate against.

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