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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds substantive behavioral context the annotations cannot: the data is a join of live in-China OONI measurement and an index over Chinese LLMs, and it is a derived convenience aggregation rather than raw payload. It stops short of stating freshness/caching or what happens if one layer is unavailable.

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?

Three short sentences, front-loaded with the scope, then the no-arg fact, then the escape hatch to get_signal. Every sentence carries distinct information with no restatement of the title or annotations.

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 zero-argument composite read with no output schema, the description tells the agent what content to expect (two joined layers) and where to get raw single-layer data instead. It leaves return shape and freshness unstated, which is a minor gap given no output schema exists to cover them.

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?

Zero parameters, so the baseline is 4; the description reinforces this with 'Takes no arguments', removing any ambiguity about needing filters. No further parameter meaning is possible or needed.

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 ('Read') and resource ('the Great Firewall's current state at both layers'), then enumerates exactly which two layers: live OONI network blocking measured inside China and model-layer censorship from the Generative Firewall Index. It also names what it is not — a single-layer view — routing to get_signal.

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?

Explicitly says 'Takes no arguments' and frames itself as 'A combined convenience view', then names the alternative path: 'for one layer's full raw payload use get_signal with ooni-gfw or generative-firewall-index'. That is a clear when-versus-when-not with the exact sibling and argument values.

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