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

With no annotations, the description carries the full burden. It does usefully disclose auth mechanics (HTTP signature headers over the full RPC body, self-custody signing the entry intent) and idempotency precedence (header wins; both must match), plus that the operation appends a tombstone rather than hard-deleting. But it omits whether deletion is reversible, what happens if `key` does not exist, whether concurrent writes conflict, and rate or permission requirements — significant gaps for a mutation with zero annotation coverage.

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?

It is front-loaded with the action, which is good, but the body is a single semicolon-chained run-on mixing auth mechanics, idempotency, and prompt-injection warnings. The untrusted-content warning is defensible but is phrased generically and inflates length relative to the tool-specific information.

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 4-parameter mutation with no annotations, no output schema, and zero schema description coverage, the definition is incomplete. It never explains the identity of `key`, the role of `if_seq` (presumably optimistic concurrency), the exact `signature` input, or what the response contains after a tombstone is appended.

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 must compensate and does so only partially. It explains idempotency_key well (argument vs header, precedence, match requirement) and gestures at `signature` via the HTTP signature mention, but `key`, `if_seq`, and the expected form of `signature` (an 86-character value) are left entirely undefined.

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?

"Append a tombstone to my vault chain" names a specific verb and mechanism, so the append-only, soft-delete nature is conveyed. However, it never states explicitly that this deletes a memory entry keyed by `key`, nor does it distinguish this from siblings such as memory_put, memory_get, or vault_head — the agent must infer the target resource from the tool name alone.

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?

There is no guidance on when to prefer this over memory_put or how it relates to the rest of the memory/vault family. The only conditional content is mechanical (idempotency_key argument vs header), not a when-to-use rule. No prerequisites about key existence or required signing identity are stated.

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