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

Annotations already declare the safety profile (non-destructive, non-idempotent, closed-world), so the bar is lower. The description adds useful behavior — the Markdown format, the 120-character title limit, and that the new bubble's id is returned — but it does not warn that repeated calls create duplicates, which is the practical consequence of idempotentHint=false.

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 short sentences, front-loaded with the action, then guidance, then the return value. Nearly zero waste; only the title-length restatement slightly overlaps the schema's maxLength.

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?

A simple four-parameter create tool with annotations covering safety and an explicit statement of the return value, so no output schema is needed. Minor gaps are the absence of duplicate-creation behavior and any content-size or format caveats.

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 coverage is 75%, so the baseline is 3. The description adds light guidance beyond the schema ("short, specific title", "set source to the app you are") and correctly notes source semantics, but it never mentions `label` or `content` beyond the format note, so it does not fully compensate for the uncovered quarter.

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 ("Save new context as a bubble") and the word "new" signals creation rather than modification. It is distinguishable from most siblings by name, but it never explicitly contrasts with update_bubble, which is the closest alternative.

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?

"Save new context" implies the usage condition (you have new content worth keeping) and "Set `source` to the app you are" is invocation guidance, but there is no explicit when-to-use/when-not or routing to update_bubble for existing bubbles. Guidance is inferable rather than stated.

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