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

Annotations already declare destructiveHint=true, idempotentHint=false, and readOnlyHint=false, so the safety profile is structured. The description adds the replace-vs-append behavioral contrast beyond the schema, but does not warn that `content` wipes all prior content irreversibly or note any permission/lookup requirements.

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?

A single sentence that front-loads the mutation scope and resolves the key ambiguity (append vs. full replace) with a parenthetical. Zero wasted words.

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?

Four fully documented parameters, annotations covering safety, and no output schema to explain — the description is sufficient to invoke correctly. It could be stronger by clarifying the save_bubble relationship or that the operation is not idempotent, but nothing essential is missing.

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 description coverage is 100%, so all four parameters are already documented, including that `append` inserts after a blank line. The description's only added nuance is that a partial update is permitted for `append`, which is marginal over the schema — baseline 3 is appropriate.

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 ('Change a bubble's title, replace its content, or add to the end of it') and enumerates the three mutation modes. It is clearly separable from get_bubble/list_bubbles/delete_bubble, but it never distinguishes itself from save_bubble, the sibling most likely to be confused with an update.

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 parenthetical 'no need to send the whole bubble again' gives a useful decision rule for choosing `append` over `content`. However, there is no guidance on when to call this at all versus save_bubble or restore_bubble, so usage context is only implied.

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