table_exists

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

With no annotations, the description carries the full burden and does state the return type (boolean) and the non-obvious semantic that views are excluded, which is the main behavioral trap. It does not cover Oracle name-matching behavior (case sensitivity) or permission/visibility effects on ALL_TABLES, which are real caveats for a lookup tool.

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, front-loaded with the outcome and mechanism, followed by the alternative to use. No filler or restatement of the name.

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 two-parameter read-only predicate tool with no output schema, the description supplies the return value and the key exclusion rule; the schema covers the optional schema param. Only minor gaps remain around name-matching conventions.

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 both parameters are already documented in the schema, including the default-to-current-schema hint and the 'omit rather than guess' guidance. The description adds nothing beyond the schema for parameters, so the baseline 3 applies.

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 ('Return true if a table exists') plus the exact resolution mechanism (ALL_TABLES) and an explicit negative scope (views are NOT considered). An agent can distinguish it from list_tables, describe_table, and search_objects without opening any schema.

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 names the alternative it replaces ('Use this instead of run_query {SELECT 1 FROM ALL_TABLES WHERE ...}') and gives the exact pattern being superseded, so the routing decision is unambiguous. The views exclusion also implicitly states when its answer will be false despite a visible object.

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