update_discussion

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

Annotations already declare destructiveHint and idempotentHint, but the description adds critical specifics beyond them: description fully REPLACES the body (forcing a read-first, send-whole-text workflow), threads cannot be moved, tags cannot be changed, and discarded threads cannot be edited. These negative constraints are exactly the context an agent needs before mutating.

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?

One dense, well-ordered sentence: identification, partial-update rule, the destructive replacement warning, then the impossibility constraints. No filler, and the highest-risk behavior (body replacement) is front-loaded.

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 13-parameter mutation tool with no output schema and strong annotation coverage, the description covers the essential behavioral traps. Minor gaps remain around recipient/notify effects and permission requirements, but the core editing contract is complete.

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 92%, so the schema carries most parameter meaning. The description still adds value by grouping the changeable fields ('allow_* flags, recipients to add') and emphasizing the replace-not-merge semantics of description, which the schema only states tersely.

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 and resource ('Edit a discussion by id_or_key'), identifies the key parameter, and scopes it as a single call. An agent can distinguish this from create_discussion or update_comment without opening the 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?

'Pass only what changes' plus the 'read it first' workflow for description give clear operational context, and the closing sentence lists what the tool cannot do. It stops short of naming a sibling alternative (e.g. update_comment) the way a 5 would, but the usage context is unambiguous.

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