edit_tool

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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description adds a real behavioral guarantee: 'Invalid edits leave the old tool intact,' implying atomic replacement. It also discloses that the management built-ins cannot be edited, which is beyond the schema and helps prevent failed calls. There is no contradiction with the annotations.

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?

The description is three sentences, front-loaded with the action and followed by the key caveats. It contains no filler and keeps the important guarantees (atomic invalid edits, protected built-ins) compactly grouped.

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 mutation tool with four required parameters and a nested object, the description covers the core replace semantics and failure atomicity, and the presence of an output schema reduces the need to explain return values. It still leaves gaps around the exact form of `input_schema` and what constitutes a 'valid' edit versus an invalid one, as well as what happens if the named tool does not exist. Given the tool's complexity, these gaps prevent a higher score.

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?

With 0% schema description coverage, the description must work harder. It connects three parameters to the operation ('description, input_schema, and Python source') and clarifies that `name` identifies the tool and all fields are required ('Supply all fields'). It does not, however, explain the expected structure of `input_schema` or the Python source format, so a meaningful parameter burden remains.

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 opens with 'Replace an existing custom tool's description, input_schema, and Python source,' a specific verb-plus-resource statement that names exactly what changes. It also states the name's identifying role and explicitly notes the built-in tools it cannot touch, which differentiates it from add_tool and remove_tool.

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 clearly scopes the tool to existing custom tools ('Replace an existing custom tool's...'), giving the agent a context for when to invoke it, and explicitly excludes the built-ins add_tool, edit_tool, and remove_tool from being edited. It does not, however, name add_tool or remove_tool as alternatives for create/delete cases, so the guidance is mostly contextual rather than a full when/when-not matrix.

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