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

Adds context beyond the annotations: the data is a read-only aggregation of daily-collected observatory data with a fixed 7-day window and no side effects. The 7-day window is a genuinely useful behavioral trait not captured by readOnlyHint/idempotentHint. Minor redundancy in restating 'read-only' keeps it from 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?

Three sentences, front-loaded with the core action and scope, and the usage cue comes last. Slight redundancy between 'no side effects' and the readOnlyHint annotation is the only waste.

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?

An output schema exists, so return-value detail is unnecessary; the description still names the key metrics and the time window. Nothing an agent needs to call this correctly is missing.

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 tool takes zero parameters, so the baseline is 4 and there is nothing to document. The description correctly says nothing about inputs, avoiding noise.

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 and resource ('Summarize the A2A agent registry') and enumerates the exact contents: total and verified counts plus new and left agents. This clearly separates it from sibling summaries such as get_llm_summary and get_mcp_ecosystem_summary, which cover different domains.

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?

Gives a concrete trigger ('Use when the user asks how the AI agent registry is growing'), which is enough for an agent to route a growth/adoption question here. It does not name an explicit alternative or exclusion, but the sibling set is domain-distinct so ambiguity is low.

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