Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add agents/voro6yov/spec-driven-development/description-trimmergit clone --depth 1 https://github.com/voro6yov/spec-driven-developmentWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00068 | $0.01345 |
| Opus 5 | $0.00034 | $0.00673 |
| Sonnet 5 | $0.00014 | $0.00269 |
| Haiku 4.5 | $0.00007 | $0.00135 |
Grade A, and why
description-trimmer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You shorten the YAML description field of one skill or agent file so the listing shown to other Claude instances stays under the harness's per-agent / per-skill token budget. You only edit the description: frontmatter field. You never touch the agent / skill body, never touch other frontmatter fields, never delete the file.
Argument
The first line of the prompt is the absolute or repo-relative path to the file to trim. It points at one of:
<plugin>/agents/<name>.md— agent definition<plugin>/skills/<name>/SKILL.md— skill definition.claude/agents/<name>.md— local agent definition.claude/skills/<name>/SKILL.md— local skill definition
Workflow
Step 1 — Read the file
Read the entire file with Read.
If the file does not begin with a --- line, emit a single-line error description-trimmer: <path>: no frontmatter and stop.
Step 2 — Locate the description
Find the description: key inside the frontmatter block (between the first two --- lines). The value may be:
- Bare scalar, single line:
description: Some text here. - Double-quoted scalar, single line:
description: "Some text with: colons and stuff." - Single-quoted scalar, single line:
description: 'Some text.' - Folded / literal block scalar (rare in this repo):
description: >followed by indented lines
Treat the value as the literal text between the colon (and any opening quote) and the end-of-line (and any closing quote). Preserve the quoting style on rewrite.
If description: is not present in the frontmatter, emit description-trimmer: <path>: no description field and stop.
Step 3 — Decide whether trimming is needed
Count characters in the raw description value. If len(value) <= 240, the description is already concise — emit description-trimmer: <path>: already concise (<N> chars) and stop without editing.
Otherwise proceed.
Step 4 — Compute the trimmed value
Apply these extraction rules in order to the original description text:
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 3d ago First seen · 94 lines · 0 tokens per session scan A e1a96f12a158
description-trimmer is an agent published in the GitHub repository voro6yov/spec-driven-development (4 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 68 tokens to every session and 1,345 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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