session_resize

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

No annotations are supplied, so the description must carry the behavioral burden. It does disclose a real behavioral trait — that attaching humans stop resizing a pinned pane, and regain that ability with fixed=false — but says nothing about persistence, error cases, or what happens when cols/rows are omitted. Partial disclosure for an unannotated mutation 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?

A single front-loaded sentence leads with the core action, then qualifies it with the default and the alternative. The nested parenthetical makes it slightly more convoluted than necessary, but nothing is wasted.

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?

With an output schema present, return values need not be explained. The description covers the resize/pin behavior adequately, but for a session-mutating tool with no annotations it omits the effect of omitted cols/rows and any failure modes or session-state requirements.

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 the schema already documents cols, rows, fixed, and session in detail. The description largely restates the `fixed` semantics already present in the schema, adding no syntax or format detail beyond it. 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 ('Set the pane size') and immediately explains the pinning semantics of the `fixed` flag. It is clearly distinct from siblings like session_split or session_create, though it never explicitly names or contrasts a sibling. A clear but not sibling-differentiating definition.

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?

Usage is implied through the two modes described (pin vs. follow the attached human's window), which tells the agent the effect of each choice. However, there is no explicit when-to-use guidance, no prerequisites, and no routing to alternatives such as session_split for layout changes.

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