invariance_session_append_note

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

Annotations already declare it a write operation (readOnlyHint=false, destructiveHint=false). The description adds that the note becomes a custom event and part of the 'company brain timeline,' which clarifies the effect beyond annotations. It doesn't mention prerequisites like session existence, but that's a minor omission for a simple append.

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?

The description is two sentences plus a compact list of use cases. It is front-loaded with the action and technical detail, then provides concrete usage scenarios. Every element earns its place, with zero fluff or redundancy.

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 simple two-parameter append with no output schema, the description covers the what, when, and effect. It lacks explicit return-value expectations or failure modes, but given the tool's simplicity and the annotations covering mutation safety, this is a minor gap. The concrete use cases make it sufficiently complete.

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 100%, with both `text` and `session_id` already described. The description reiterates 'freeform' and 'existing session,' which adds no new meaning beyond the schema. With full schema coverage, the baseline of 3 is appropriate; the description does not compensate for any missing semantic detail.

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 opens with a specific verb-resource pair: 'Append a freeform text note to an existing session' and details the technical mechanism ('as a custom event with payload {text}'). It lists concrete use cases (jotting thoughts, meeting takeaways, screen annotations, transcript chunks) that clearly differentiate it from sibling tools like session creation, run attachment, or KB summary recording.

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 'USE THIS WHEN:' section enumerates four specific scenarios, leaving no ambiguity about intended usage. It implicitly contrasts with alternatives by focusing on freeform text notes rather than structured attachments or summaries, guiding an agent to the right tool without mentioning exclusions.

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