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

With no annotations, the description carries the full burden, but it does disclose two real behavioral traits: the call is free and results are ordered by registration recency. It omits how many agents are returned, whether there is a cap or pagination, and any auth requirements, so it is partial rather than complete.

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?

A single short sentence with the key qualifier ('Free') front-loaded and zero filler. Nothing to trim.

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-param list tool with no output schema and no annotations, the description covers purpose and ordering but leaves open the return volume, pagination or truncation behavior, and whether authentication is required. Adequate but with clear gaps.

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?

The schema takes zero parameters, so there is nothing for the description to disambiguate; baseline is 4. The 'most recently registered' phrase at least characterizes the implicit result set, but there are no parameter semantics to add meaning to.

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 (list) and resource (agents) with a scope qualifier (most recently registered). It is legible against siblings like get_agent or register_agent, but the description never explicitly distinguishes itself from them, so it falls 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?

There is no when-to-use guidance, no mention of the alternative (get_agent for a single agent), and no stated prerequisites. The only usage-adjacent signal is the word 'Free', which hints at a cost consideration but does not guide selection.

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