Create Exploratory Session

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

Annotations only declare readOnlyHint=false / destructiveHint=false, so the description carries real added weight: write-permission requirement, server-side email resolution for assigneeUserId, automatic normalization of state values so UI colors render, and the fact that findings and attachments are simply not available over MCP (400 refusal). These are non-obvious behaviors an agent would otherwise discover only by failing.

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?

Front-loaded with purpose, then prerequisites, then per-parameter gotchas, ending on the highest-risk warning (tags format). A couple of clauses restate schema text verbatim ("estimate is in minutes", the tags example), which is mild redundancy, but nothing is filler.

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 with no output schema, the description covers the highest-risk unknowns: permissions, unsupported fields, and the tags format trap. It does not say what the call returns (e.g. whether the new session _id comes back), and the config/environment parameters are undocumented in both schema and description, leaving a small gap.

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 85%, so the schema already does most of the work; the description still adds value by explaining that mission accepts rich HTML, that assigneeUserId takes either a User _id or an email resolved against TestDino users, and that estimate is in minutes. The tags array-vs-comma-separated warning is repeated from the schema but is framed as a failure mode, which is useful reinforcement.

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?

Opens with a specific verb+resource: "Create a new exploratory testing session." It is immediately distinguishable from siblings like list_sessions, get_session, and update_session, and the mention of list_sessions' comma-separated tag filter further separates the create path from the list path.

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?

States a hard prerequisite ("Requires write permission") and gives explicit fallback routing for unsupported work: findings must be added in the UI, attachments are refused. It does not explicitly say when to call this versus update_session, but the create-vs-update distinction is inferable from the name and the rest of the guidance is concrete.

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