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

The description goes beyond the readOnlyHint annotation by explaining the semantic meaning of the damage modifiers ('weak_to' means more than 100% damage, 'resistant_to' means less). This is critical for correct filter usage and is not derivable from the schema alone. It does not mention pagination or return format, but annotations already indicate a read-only, safe operation, and output schema exists.

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?

Two sentences with no filler. The first sentence states the purpose, the second immediately clarifies the most non-trivial semantic detail and provides an example. Information is front-loaded and every word earns its place.

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?

Given 13 parameters and an output schema, the description covers the essential tricky part (damage modifiers) and gives a usage example. It does not explain defaults for parameters like limit, sort, or include_inactive, but those are present in the schema. The exclusion of unrecorded hitpoints is documented in the schema for the relevant parameters. Overall, the description is sufficient for an agent to call the tool correctly, though it could explicitly mention that filters combine logically and that results are returned as a list.

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 only 38%, leaving many parameters (sort, limit, cursor, is_boss, experience_min/max, etc.) undocumented in both schema and description. The description compensates for the damage-modifier parameters (weak_to, resistant_to) by explaining their meaning, but does not add value for the remaining parameters, which are fairly self-explanatory but still nominally under-documented. This partial compensation warrants a 3.

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 description clearly states the verb ('Find') and the resource ('Tibia creatures') with a specific scope ('matching stat filters'). It distinguishes from siblings: tibia_get and tibia_search likely retrieve specific entities, tibia_find_items is for items, and tibia_how_to_obtain is a process. The tool's purpose is unambiguous.

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?

The description provides a concrete example of when to use the tool ('which creatures are weak to fire and give over 500 experience'), which strongly implies typical usage scenarios. It does not explicitly mention alternatives or when not to use this tool, but the example is illustrative enough for an agent to recognize suitable queries.

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