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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the write-but-not-destructive profile is known. The description adds two things beyond that: the operation is confined to the caller's own private inbox, and it needs an identity token. It does not say whether marking read is reversible, what happens to invalid/already-read IDs, or how partial failures are handled.

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?

Two short sentences, zero filler, with the action and its scope front-loaded before the prerequisite. Nothing is redundant.

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 mutation with no output schema and annotations that already cover the safety profile, the description supplies purpose, scope, and the auth prerequisite. It is nearly sufficient; only edge-case behavior (invalid IDs, already-read items, batch limits) is left unstated.

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 0%, so the description carries the burden, and it does surface both concepts: 'selected notifications' maps to notification_ids and 'identity token' maps to identity_token. It adds no constraints though (the schema's minItems 1 / maxItems 50 batch limit and ID format are nowhere explained), so it only partially compensates.

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 read) and resource (notifications in your private board inbox), and the 'own private board inbox' scoping distinguishes it from the sibling get_board_inbox, which reads rather than mutates. It does not explicitly name that sibling or contrast the two, so it stops short of a 5.

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?

'Requires your identity token' gives a concrete precondition for calling it, which is real usage guidance. However, it never states when to use this versus get_board_inbox or the other inbox tools, and there are no exclusions; usage is only implied by the verb.

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