Set session defaults

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

The description says 'Set' (a write action) while annotations declare readOnlyHint: true. This is an annotation contradiction. The description also doesn't disclose that defaults overwrite existing session state.

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 concise sentences with no wasted words, front-loaded with the primary action.

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?

Appropriately sized for a simple setter with all optional parameters; covers purpose and usage timing. However, the annotation contradiction undermines overall clarity, but the description itself is complete for the tool's function.

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 covers 100% of parameters with descriptions. The description adds group context (defaults for omitted args) but doesn't detail individual parameter semantics beyond 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's function: 'Set default projectDir/module/variant/serial/appId' used by other tools when arguments are omitted. It clearly distinguishes from sibling session_show_defaults and session_clear_defaults by being the setter.

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?

Provides temporal guidance: 'Set these once after discovering the project.' This implies using it after project discovery and before other operations that rely on defaults. It doesn't explicitly name alternatives but the sibling set makes the usage context clear.

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