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

With no annotations, the description carries the full burden and does disclose real behavioral traits: a free catalog tier, a $0.003 paid unlock with <40ms latency, and zero charge on unknown keys. What it omits is what a 'delta' actually contains and whether the catalog listing and the unlocked content differ in shape.

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 short, but the information hierarchy is inverted: pricing leads and purpose follows. The four inline topic-key examples are the most useful content and consume the most space, while the one thing an agent most needs — what comes back — is absent.

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 one-optional-parameter tool with no annotations and no output schema, the cost model and trigger conditions are covered, but the return shape is entirely undocumented — an agent cannot tell whether omitting topic_key yields key names only or full notes, which matters for planning a second paid call.

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 single parameter's schema already says to omit it for a free catalog listing. The description restates that dichotomy without adding format, key syntax rules, or what happens when a partially-matching key is supplied.

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 reader must infer the purpose from examples and the phrase 'Prevents deprecated parameter hallucinations' — the tool is never stated plainly as 'returns verified breaking-change notes for a topic key.' The opening clause is about pricing tiers rather than what the tool does, and nothing distinguishes it from the sibling unlock_verified_fix.

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?

'Call BEFORE writing code against post-cutoff SDKs or selecting LLM model IDs' gives a concrete trigger condition and timing, which is genuinely useful routing guidance. It stops short of saying when NOT to use it or why one would pick this over unlock_verified_fix or check_upstream_pulse.

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