set_session_cookie

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

No annotations, so the description carries the full burden. It does add real behavioral context by explaining this is a manual substitute for browser login, but it omits key traits: whether it overwrites an existing cookie, whether the value is validated, what happens on an invalid/expired cookie, and whether the session persists across calls.

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?

One sentence with a purposeful parenthetical; nothing is padding and the core action is front-loaded before the use-case qualifier.

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 single-parameter setter with full schema coverage and no output schema, the description covers purpose and scenario adequately. It could be stronger by explicitly relating itself to interactive_login as the alternative auth path and noting error/validation behavior, but the essentials are present.

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% and the schema already explains the single 'value' parameter and where to obtain it (DevTools). The description adds no format, validation, or encoding detail beyond the schema, so the baseline of 3 applies.

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 MoodleSession cookie'), which is unambiguous and distinguishable from list/scrape siblings. The parenthetical about headless VMs further narrows the scenario, though it never names the browser-based alternative (interactive_login) directly.

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?

Gives a clear when-to-use condition: headless VMs where a browser isn't available. It implies the alternative (browser-based interactive login) without explicitly naming it or stating exclusions, so it falls just short of full when/when-not guidance.

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