Call a read-only tool

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

Annotations already declare readOnlyHint=true, and the description is consistent while adding real value: it discloses the success return ("the tool's own result") and the failure mode ("what is wrong and the schema") when arguments do not fit. It does not address openWorldHint=true or idempotentHint=false, so the agent gets no warning that repeated reads may yield different results.

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 tightly packed sentences with no filler: the scope and eligibility rule come first, then return/error behavior, then the refusal rule. Every clause carries actionable information.

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 dispatch tool with no output schema, it covers eligibility, argument source, return shape, and refusal behavior. Minor omissions remain: how to obtain the schema (search_tools vs describe_tool ordering) and the distinction from the sibling call_read_tools.

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 coverage is 100%, so the schema already documents name and arguments, and the description largely restates them. It adds marginal provenance value by tying name to search_tools and arguments to the tool's own input schema, but no guidance on the nested arguments object beyond that.

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 ("call a tool that only reads") plus the exact selection criterion (readOnly in search_tools results), and names the write-tool counterpart. An agent can tell it apart from call_write_tool without opening either 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?

Gives a clear when-to-use rule keyed to the readOnly flag and an explicit alternative ("call those with call_write_tool"), which is strong guidance. The gap is that the sibling call_read_tools (plural, batch variant) is never mentioned, leaving the agent to guess which of the two read paths to pick.

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