query_mass_entities

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive). The description adds value by disclosing the return shape (matching_count, fragment, tag, presence), which matters since there is no output schema, and by clarifying the fragment-vs-tag requirement logic.

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 tight sentences, front-loaded with the core purpose and returning shape; nothing is padded. The 'Requires fragment' statement is slightly at odds with the schema's zero required params, which adds a small ambiguity.

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 read-only query tool with annotations and no output schema, the description covers purpose, parameter logic, and the return fields. It would be stronger if it clarified the fragment/tag-optional relationship and distinguished itself from the sibling count tool.

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 100%, so the baseline is 3. The description largely mirrors the schema's parameter docs (fragment format, presence values) rather than adding syntax or behavioral detail beyond it.

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+resource ('Count entities matching a fragment/tag requirement'), which is clear and operational. However, it does not distinguish itself from the sibling 'count_mass_entities' or 'get_mass_entity_info', leaving an agent unsure which count tool to pick.

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?

It gives conditional usage for the parameters (fragment for fragment queries, tag for tag-only), which is genuine guidance. But it offers no when-to-use context relative to the many mass-entity siblings, so the agent must infer which tool applies.

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