mark_message

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

No annotations, so the description carries the full burden. It conveys that this mutates read state but says nothing about idempotency, whether the change is reversible, or that a toggle-style boolean controls direction. For a mutation tool with zero annotation coverage this is thin.

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 short sentence with the action front-loaded and no filler. It is efficient, though brevity here shades into under-specification rather than tightness.

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 tool with no output schema, the description covers the core action. However, with no annotations and an undocumented `unread` parameter, it leaves an agent guessing at permission needs and the boolean's polarity.

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 50%: `id` is documented in the schema, `unread` is not. The description implies the boolean selects between marking read and unread, partially compensating, but it never states which value maps to which state, leaving the key semantic gap unfilled.

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 (mark) and resource (message) plus the two resulting states (read/unread), so the action is unambiguous. It does not explicitly contrast itself with siblings like read_message or list_messages, but the verb distinguishes it adequately.

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?

No guidance on when to use this versus alternatives such as read_message (which likely also affects read state) or list_messages. No prerequisites, no mention that an id from list_messages is required (that hint lives only in the schema).

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