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

Annotations declare readOnlyHint=false for what looks like a pure read; the description resolves that apparent conflict by disclosing that a read 'may renew sliding TTL with write access', and it adds a failure behavior ('refuses burn values'). It does not say what happens when the key is absent, so it falls short of a 5.

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 dense sentences with the return payload front-loaded and side effects immediately after; no filler. Terms like 'burn values' and 'sliding TTL' assume domain familiarity, which slightly reduces standalone clarity.

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?

There is no output schema, and the description names the return contents (value, metadata, ETag) as well as the TTL side effect, which is enough to call the tool. The not-found / error path is the one meaningful omission for a single-key lookup.

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 was expected to compensate, and it does not — it says nothing about what 'key' means or its format. The schema's own regex pattern supplies the naming constraint, keeping this at a baseline 3 rather than lower.

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?

The verb 'Read' plus the precise payload ('exact string value, metadata and ETag') tells an agent exactly what the call returns. It is not fully distinguished from the sibling get_metadata, which likely overlaps on the metadata portion, so a 4 rather than 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?

Usage is implied (fetch a stored value) and there is one explicit exclusion — it 'refuses burn values' — but no alternative tool is named for that case, and nothing says when to prefer this over get_metadata or touch_key.

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