persona_update

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

There are no annotations, so the description carries the transparency burden. It adds valuable non-obvious behavior: the persona is injected at SessionStart, it costs roughly 50 tokens per session, and no LLM call is needed—the agent writes the trait/value directly. It does not mention overwrite semantics, permissions, or confirmation output, but it provides stronger behavioral context than a typical update tool.

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 tight sentences front-load the action and trigger, then add only high-value operational details: automatic SessionStart injection, token impact, and no-LLM requirement. Nothing in the description is filler or redundant.

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 write-only utility with six schema-covered parameters, the description covers the when, the why, and the important side effect (automatic session injection). A brief note on confirmation or return behavior would make it fully complete, but the core invocation context is well covered.

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 input schema already has 100% coverage with clear parameter descriptions, so the schema is doing the heavy lifting. The description's examples ('Vietnamese', 'concise', 'AZR') reinforce the trait/value semantics but add little new meaning. This is the standard '3' baseline for high schema coverage.

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 clearly states the action and target: 'Update the L3 persona profile for this user/team.' Concrete examples ('prefers concise output', 'works in Vietnamese', 'uses AZR project') further clarify what the tool is for. It does not explicitly differentiate from sibling memory tools like capture or update, but the L3 persona resource is distinctive enough.

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 an explicit trigger: 'Call this when you notice a user preference or pattern.' The examples make the trigger concrete and actionable. It does not state when NOT to use the tool or name alternatives, so it stops short of full routing guidance.

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